Metamath Proof Explorer


Theorem rplogsumlem1

Description: Lemma for rplogsum . (Contributed by Mario Carneiro, 2-May-2016)

Ref Expression
Assertion rplogsumlem1 ( 𝐴 ∈ ℕ → Σ 𝑛 ∈ ( 2 ... 𝐴 ) ( ( log ‘ 𝑛 ) / ( 𝑛 · ( 𝑛 − 1 ) ) ) ≤ 2 )

Proof

Step Hyp Ref Expression
1 fzfid ⊢ ( 𝐴 ∈ ℕ → ( 2 ... 𝐴 ) ∈ Fin )
2 elfzuz ⊢ ( 𝑛 ∈ ( 2 ... 𝐴 ) → 𝑛 ∈ ( ℤ≥ ‘ 2 ) )
3 eluz2nn ⊢ ( 𝑛 ∈ ( ℤ≥ ‘ 2 ) → 𝑛 ∈ ℕ )
4 2 3 syl ⊢ ( 𝑛 ∈ ( 2 ... 𝐴 ) → 𝑛 ∈ ℕ )
5 4 adantl ⊢ ( ( 𝐴 ∈ ℕ ∧ 𝑛 ∈ ( 2 ... 𝐴 ) ) → 𝑛 ∈ ℕ )
6 5 nnrpd ⊢ ( ( 𝐴 ∈ ℕ ∧ 𝑛 ∈ ( 2 ... 𝐴 ) ) → 𝑛 ∈ ℝ+ )
7 6 relogcld ⊢ ( ( 𝐴 ∈ ℕ ∧ 𝑛 ∈ ( 2 ... 𝐴 ) ) → ( log ‘ 𝑛 ) ∈ ℝ )
8 2 adantl ⊢ ( ( 𝐴 ∈ ℕ ∧ 𝑛 ∈ ( 2 ... 𝐴 ) ) → 𝑛 ∈ ( ℤ≥ ‘ 2 ) )
9 uz2m1nn ⊢ ( 𝑛 ∈ ( ℤ≥ ‘ 2 ) → ( 𝑛 − 1 ) ∈ ℕ )
10 8 9 syl ⊢ ( ( 𝐴 ∈ ℕ ∧ 𝑛 ∈ ( 2 ... 𝐴 ) ) → ( 𝑛 − 1 ) ∈ ℕ )
11 5 10 nnmulcld ⊢ ( ( 𝐴 ∈ ℕ ∧ 𝑛 ∈ ( 2 ... 𝐴 ) ) → ( 𝑛 · ( 𝑛 − 1 ) ) ∈ ℕ )
12 7 11 nndivred ⊢ ( ( 𝐴 ∈ ℕ ∧ 𝑛 ∈ ( 2 ... 𝐴 ) ) → ( ( log ‘ 𝑛 ) / ( 𝑛 · ( 𝑛 − 1 ) ) ) ∈ ℝ )
13 1 12 fsumrecl ⊢ ( 𝐴 ∈ ℕ → Σ 𝑛 ∈ ( 2 ... 𝐴 ) ( ( log ‘ 𝑛 ) / ( 𝑛 · ( 𝑛 − 1 ) ) ) ∈ ℝ )
14 2re ⊢ 2 ∈ ℝ
15 10 nnrpd ⊢ ( ( 𝐴 ∈ ℕ ∧ 𝑛 ∈ ( 2 ... 𝐴 ) ) → ( 𝑛 − 1 ) ∈ ℝ+ )
16 15 rpsqrtcld ⊢ ( ( 𝐴 ∈ ℕ ∧ 𝑛 ∈ ( 2 ... 𝐴 ) ) → ( √ ‘ ( 𝑛 − 1 ) ) ∈ ℝ+ )
17 rerpdivcl ⊢ ( ( 2 ∈ ℝ ∧ ( √ ‘ ( 𝑛 − 1 ) ) ∈ ℝ+ ) → ( 2 / ( √ ‘ ( 𝑛 − 1 ) ) ) ∈ ℝ )
18 14 16 17 sylancr ⊢ ( ( 𝐴 ∈ ℕ ∧ 𝑛 ∈ ( 2 ... 𝐴 ) ) → ( 2 / ( √ ‘ ( 𝑛 − 1 ) ) ) ∈ ℝ )
19 6 rpsqrtcld ⊢ ( ( 𝐴 ∈ ℕ ∧ 𝑛 ∈ ( 2 ... 𝐴 ) ) → ( √ ‘ 𝑛 ) ∈ ℝ+ )
20 rerpdivcl ⊢ ( ( 2 ∈ ℝ ∧ ( √ ‘ 𝑛 ) ∈ ℝ+ ) → ( 2 / ( √ ‘ 𝑛 ) ) ∈ ℝ )
21 14 19 20 sylancr ⊢ ( ( 𝐴 ∈ ℕ ∧ 𝑛 ∈ ( 2 ... 𝐴 ) ) → ( 2 / ( √ ‘ 𝑛 ) ) ∈ ℝ )
22 18 21 resubcld ⊢ ( ( 𝐴 ∈ ℕ ∧ 𝑛 ∈ ( 2 ... 𝐴 ) ) → ( ( 2 / ( √ ‘ ( 𝑛 − 1 ) ) ) − ( 2 / ( √ ‘ 𝑛 ) ) ) ∈ ℝ )
23 1 22 fsumrecl ⊢ ( 𝐴 ∈ ℕ → Σ 𝑛 ∈ ( 2 ... 𝐴 ) ( ( 2 / ( √ ‘ ( 𝑛 − 1 ) ) ) − ( 2 / ( √ ‘ 𝑛 ) ) ) ∈ ℝ )
24 14 a1i ⊢ ( 𝐴 ∈ ℕ → 2 ∈ ℝ )
25 16 rpred ⊢ ( ( 𝐴 ∈ ℕ ∧ 𝑛 ∈ ( 2 ... 𝐴 ) ) → ( √ ‘ ( 𝑛 − 1 ) ) ∈ ℝ )
26 5 nnred ⊢ ( ( 𝐴 ∈ ℕ ∧ 𝑛 ∈ ( 2 ... 𝐴 ) ) → 𝑛 ∈ ℝ )
27 peano2rem ⊢ ( 𝑛 ∈ ℝ → ( 𝑛 − 1 ) ∈ ℝ )
28 26 27 syl ⊢ ( ( 𝐴 ∈ ℕ ∧ 𝑛 ∈ ( 2 ... 𝐴 ) ) → ( 𝑛 − 1 ) ∈ ℝ )
29 26 28 remulcld ⊢ ( ( 𝐴 ∈ ℕ ∧ 𝑛 ∈ ( 2 ... 𝐴 ) ) → ( 𝑛 · ( 𝑛 − 1 ) ) ∈ ℝ )
30 29 22 remulcld ⊢ ( ( 𝐴 ∈ ℕ ∧ 𝑛 ∈ ( 2 ... 𝐴 ) ) → ( ( 𝑛 · ( 𝑛 − 1 ) ) · ( ( 2 / ( √ ‘ ( 𝑛 − 1 ) ) ) − ( 2 / ( √ ‘ 𝑛 ) ) ) ) ∈ ℝ )
31 5 nncnd ⊢ ( ( 𝐴 ∈ ℕ ∧ 𝑛 ∈ ( 2 ... 𝐴 ) ) → 𝑛 ∈ ℂ )
32 ax-1cn ⊢ 1 ∈ ℂ
33 npcan ⊢ ( ( 𝑛 ∈ ℂ ∧ 1 ∈ ℂ ) → ( ( 𝑛 − 1 ) + 1 ) = 𝑛 )
34 31 32 33 sylancl ⊢ ( ( 𝐴 ∈ ℕ ∧ 𝑛 ∈ ( 2 ... 𝐴 ) ) → ( ( 𝑛 − 1 ) + 1 ) = 𝑛 )
35 34 fveq2d ⊢ ( ( 𝐴 ∈ ℕ ∧ 𝑛 ∈ ( 2 ... 𝐴 ) ) → ( log ‘ ( ( 𝑛 − 1 ) + 1 ) ) = ( log ‘ 𝑛 ) )
36 15 rpge0d ⊢ ( ( 𝐴 ∈ ℕ ∧ 𝑛 ∈ ( 2 ... 𝐴 ) ) → 0 ≤ ( 𝑛 − 1 ) )
37 loglesqrt ⊢ ( ( ( 𝑛 − 1 ) ∈ ℝ ∧ 0 ≤ ( 𝑛 − 1 ) ) → ( log ‘ ( ( 𝑛 − 1 ) + 1 ) ) ≤ ( √ ‘ ( 𝑛 − 1 ) ) )
38 28 36 37 syl2anc ⊢ ( ( 𝐴 ∈ ℕ ∧ 𝑛 ∈ ( 2 ... 𝐴 ) ) → ( log ‘ ( ( 𝑛 − 1 ) + 1 ) ) ≤ ( √ ‘ ( 𝑛 − 1 ) ) )
39 35 38 eqbrtrrd ⊢ ( ( 𝐴 ∈ ℕ ∧ 𝑛 ∈ ( 2 ... 𝐴 ) ) → ( log ‘ 𝑛 ) ≤ ( √ ‘ ( 𝑛 − 1 ) ) )
40 19 rpred ⊢ ( ( 𝐴 ∈ ℕ ∧ 𝑛 ∈ ( 2 ... 𝐴 ) ) → ( √ ‘ 𝑛 ) ∈ ℝ )
41 40 25 readdcld ⊢ ( ( 𝐴 ∈ ℕ ∧ 𝑛 ∈ ( 2 ... 𝐴 ) ) → ( ( √ ‘ 𝑛 ) + ( √ ‘ ( 𝑛 − 1 ) ) ) ∈ ℝ )
42 remulcl ⊢ ( ( ( √ ‘ 𝑛 ) ∈ ℝ ∧ 2 ∈ ℝ ) → ( ( √ ‘ 𝑛 ) · 2 ) ∈ ℝ )
43 40 14 42 sylancl ⊢ ( ( 𝐴 ∈ ℕ ∧ 𝑛 ∈ ( 2 ... 𝐴 ) ) → ( ( √ ‘ 𝑛 ) · 2 ) ∈ ℝ )
44 40 25 resubcld ⊢ ( ( 𝐴 ∈ ℕ ∧ 𝑛 ∈ ( 2 ... 𝐴 ) ) → ( ( √ ‘ 𝑛 ) − ( √ ‘ ( 𝑛 − 1 ) ) ) ∈ ℝ )
45 26 lem1d ⊢ ( ( 𝐴 ∈ ℕ ∧ 𝑛 ∈ ( 2 ... 𝐴 ) ) → ( 𝑛 − 1 ) ≤ 𝑛 )
46 6 rpge0d ⊢ ( ( 𝐴 ∈ ℕ ∧ 𝑛 ∈ ( 2 ... 𝐴 ) ) → 0 ≤ 𝑛 )
47 28 36 26 46 sqrtled ⊢ ( ( 𝐴 ∈ ℕ ∧ 𝑛 ∈ ( 2 ... 𝐴 ) ) → ( ( 𝑛 − 1 ) ≤ 𝑛 ↔ ( √ ‘ ( 𝑛 − 1 ) ) ≤ ( √ ‘ 𝑛 ) ) )
48 45 47 mpbid ⊢ ( ( 𝐴 ∈ ℕ ∧ 𝑛 ∈ ( 2 ... 𝐴 ) ) → ( √ ‘ ( 𝑛 − 1 ) ) ≤ ( √ ‘ 𝑛 ) )
49 40 25 subge0d ⊢ ( ( 𝐴 ∈ ℕ ∧ 𝑛 ∈ ( 2 ... 𝐴 ) ) → ( 0 ≤ ( ( √ ‘ 𝑛 ) − ( √ ‘ ( 𝑛 − 1 ) ) ) ↔ ( √ ‘ ( 𝑛 − 1 ) ) ≤ ( √ ‘ 𝑛 ) ) )
50 48 49 mpbird ⊢ ( ( 𝐴 ∈ ℕ ∧ 𝑛 ∈ ( 2 ... 𝐴 ) ) → 0 ≤ ( ( √ ‘ 𝑛 ) − ( √ ‘ ( 𝑛 − 1 ) ) ) )
51 25 40 40 48 leadd2dd ⊢ ( ( 𝐴 ∈ ℕ ∧ 𝑛 ∈ ( 2 ... 𝐴 ) ) → ( ( √ ‘ 𝑛 ) + ( √ ‘ ( 𝑛 − 1 ) ) ) ≤ ( ( √ ‘ 𝑛 ) + ( √ ‘ 𝑛 ) ) )
52 19 rpcnd ⊢ ( ( 𝐴 ∈ ℕ ∧ 𝑛 ∈ ( 2 ... 𝐴 ) ) → ( √ ‘ 𝑛 ) ∈ ℂ )
53 52 times2d ⊢ ( ( 𝐴 ∈ ℕ ∧ 𝑛 ∈ ( 2 ... 𝐴 ) ) → ( ( √ ‘ 𝑛 ) · 2 ) = ( ( √ ‘ 𝑛 ) + ( √ ‘ 𝑛 ) ) )
54 51 53 breqtrrd ⊢ ( ( 𝐴 ∈ ℕ ∧ 𝑛 ∈ ( 2 ... 𝐴 ) ) → ( ( √ ‘ 𝑛 ) + ( √ ‘ ( 𝑛 − 1 ) ) ) ≤ ( ( √ ‘ 𝑛 ) · 2 ) )
55 41 43 44 50 54 lemul1ad ⊢ ( ( 𝐴 ∈ ℕ ∧ 𝑛 ∈ ( 2 ... 𝐴 ) ) → ( ( ( √ ‘ 𝑛 ) + ( √ ‘ ( 𝑛 − 1 ) ) ) · ( ( √ ‘ 𝑛 ) − ( √ ‘ ( 𝑛 − 1 ) ) ) ) ≤ ( ( ( √ ‘ 𝑛 ) · 2 ) · ( ( √ ‘ 𝑛 ) − ( √ ‘ ( 𝑛 − 1 ) ) ) ) )
56 31 sqsqrtd ⊢ ( ( 𝐴 ∈ ℕ ∧ 𝑛 ∈ ( 2 ... 𝐴 ) ) → ( ( √ ‘ 𝑛 ) ↑ 2 ) = 𝑛 )
57 subcl ⊢ ( ( 𝑛 ∈ ℂ ∧ 1 ∈ ℂ ) → ( 𝑛 − 1 ) ∈ ℂ )
58 31 32 57 sylancl ⊢ ( ( 𝐴 ∈ ℕ ∧ 𝑛 ∈ ( 2 ... 𝐴 ) ) → ( 𝑛 − 1 ) ∈ ℂ )
59 58 sqsqrtd ⊢ ( ( 𝐴 ∈ ℕ ∧ 𝑛 ∈ ( 2 ... 𝐴 ) ) → ( ( √ ‘ ( 𝑛 − 1 ) ) ↑ 2 ) = ( 𝑛 − 1 ) )
60 56 59 oveq12d ⊢ ( ( 𝐴 ∈ ℕ ∧ 𝑛 ∈ ( 2 ... 𝐴 ) ) → ( ( ( √ ‘ 𝑛 ) ↑ 2 ) − ( ( √ ‘ ( 𝑛 − 1 ) ) ↑ 2 ) ) = ( 𝑛 − ( 𝑛 − 1 ) ) )
61 16 rpcnd ⊢ ( ( 𝐴 ∈ ℕ ∧ 𝑛 ∈ ( 2 ... 𝐴 ) ) → ( √ ‘ ( 𝑛 − 1 ) ) ∈ ℂ )
62 subsq ⊢ ( ( ( √ ‘ 𝑛 ) ∈ ℂ ∧ ( √ ‘ ( 𝑛 − 1 ) ) ∈ ℂ ) → ( ( ( √ ‘ 𝑛 ) ↑ 2 ) − ( ( √ ‘ ( 𝑛 − 1 ) ) ↑ 2 ) ) = ( ( ( √ ‘ 𝑛 ) + ( √ ‘ ( 𝑛 − 1 ) ) ) · ( ( √ ‘ 𝑛 ) − ( √ ‘ ( 𝑛 − 1 ) ) ) ) )
63 52 61 62 syl2anc ⊢ ( ( 𝐴 ∈ ℕ ∧ 𝑛 ∈ ( 2 ... 𝐴 ) ) → ( ( ( √ ‘ 𝑛 ) ↑ 2 ) − ( ( √ ‘ ( 𝑛 − 1 ) ) ↑ 2 ) ) = ( ( ( √ ‘ 𝑛 ) + ( √ ‘ ( 𝑛 − 1 ) ) ) · ( ( √ ‘ 𝑛 ) − ( √ ‘ ( 𝑛 − 1 ) ) ) ) )
64 nncan ⊢ ( ( 𝑛 ∈ ℂ ∧ 1 ∈ ℂ ) → ( 𝑛 − ( 𝑛 − 1 ) ) = 1 )
65 31 32 64 sylancl ⊢ ( ( 𝐴 ∈ ℕ ∧ 𝑛 ∈ ( 2 ... 𝐴 ) ) → ( 𝑛 − ( 𝑛 − 1 ) ) = 1 )
66 60 63 65 3eqtr3d ⊢ ( ( 𝐴 ∈ ℕ ∧ 𝑛 ∈ ( 2 ... 𝐴 ) ) → ( ( ( √ ‘ 𝑛 ) + ( √ ‘ ( 𝑛 − 1 ) ) ) · ( ( √ ‘ 𝑛 ) − ( √ ‘ ( 𝑛 − 1 ) ) ) ) = 1 )
67 2cn ⊢ 2 ∈ ℂ
68 67 a1i ⊢ ( ( 𝐴 ∈ ℕ ∧ 𝑛 ∈ ( 2 ... 𝐴 ) ) → 2 ∈ ℂ )
69 44 recnd ⊢ ( ( 𝐴 ∈ ℕ ∧ 𝑛 ∈ ( 2 ... 𝐴 ) ) → ( ( √ ‘ 𝑛 ) − ( √ ‘ ( 𝑛 − 1 ) ) ) ∈ ℂ )
70 52 68 69 mulassd ⊢ ( ( 𝐴 ∈ ℕ ∧ 𝑛 ∈ ( 2 ... 𝐴 ) ) → ( ( ( √ ‘ 𝑛 ) · 2 ) · ( ( √ ‘ 𝑛 ) − ( √ ‘ ( 𝑛 − 1 ) ) ) ) = ( ( √ ‘ 𝑛 ) · ( 2 · ( ( √ ‘ 𝑛 ) − ( √ ‘ ( 𝑛 − 1 ) ) ) ) ) )
71 55 66 70 3brtr3d ⊢ ( ( 𝐴 ∈ ℕ ∧ 𝑛 ∈ ( 2 ... 𝐴 ) ) → 1 ≤ ( ( √ ‘ 𝑛 ) · ( 2 · ( ( √ ‘ 𝑛 ) − ( √ ‘ ( 𝑛 − 1 ) ) ) ) ) )
72 1red ⊢ ( ( 𝐴 ∈ ℕ ∧ 𝑛 ∈ ( 2 ... 𝐴 ) ) → 1 ∈ ℝ )
73 remulcl ⊢ ( ( 2 ∈ ℝ ∧ ( ( √ ‘ 𝑛 ) − ( √ ‘ ( 𝑛 − 1 ) ) ) ∈ ℝ ) → ( 2 · ( ( √ ‘ 𝑛 ) − ( √ ‘ ( 𝑛 − 1 ) ) ) ) ∈ ℝ )
74 14 44 73 sylancr ⊢ ( ( 𝐴 ∈ ℕ ∧ 𝑛 ∈ ( 2 ... 𝐴 ) ) → ( 2 · ( ( √ ‘ 𝑛 ) − ( √ ‘ ( 𝑛 − 1 ) ) ) ) ∈ ℝ )
75 40 74 remulcld ⊢ ( ( 𝐴 ∈ ℕ ∧ 𝑛 ∈ ( 2 ... 𝐴 ) ) → ( ( √ ‘ 𝑛 ) · ( 2 · ( ( √ ‘ 𝑛 ) − ( √ ‘ ( 𝑛 − 1 ) ) ) ) ) ∈ ℝ )
76 72 75 16 lemul1d ⊢ ( ( 𝐴 ∈ ℕ ∧ 𝑛 ∈ ( 2 ... 𝐴 ) ) → ( 1 ≤ ( ( √ ‘ 𝑛 ) · ( 2 · ( ( √ ‘ 𝑛 ) − ( √ ‘ ( 𝑛 − 1 ) ) ) ) ) ↔ ( 1 · ( √ ‘ ( 𝑛 − 1 ) ) ) ≤ ( ( ( √ ‘ 𝑛 ) · ( 2 · ( ( √ ‘ 𝑛 ) − ( √ ‘ ( 𝑛 − 1 ) ) ) ) ) · ( √ ‘ ( 𝑛 − 1 ) ) ) ) )
77 71 76 mpbid ⊢ ( ( 𝐴 ∈ ℕ ∧ 𝑛 ∈ ( 2 ... 𝐴 ) ) → ( 1 · ( √ ‘ ( 𝑛 − 1 ) ) ) ≤ ( ( ( √ ‘ 𝑛 ) · ( 2 · ( ( √ ‘ 𝑛 ) − ( √ ‘ ( 𝑛 − 1 ) ) ) ) ) · ( √ ‘ ( 𝑛 − 1 ) ) ) )
78 61 mullidd ⊢ ( ( 𝐴 ∈ ℕ ∧ 𝑛 ∈ ( 2 ... 𝐴 ) ) → ( 1 · ( √ ‘ ( 𝑛 − 1 ) ) ) = ( √ ‘ ( 𝑛 − 1 ) ) )
79 74 recnd ⊢ ( ( 𝐴 ∈ ℕ ∧ 𝑛 ∈ ( 2 ... 𝐴 ) ) → ( 2 · ( ( √ ‘ 𝑛 ) − ( √ ‘ ( 𝑛 − 1 ) ) ) ) ∈ ℂ )
80 52 79 61 mul32d ⊢ ( ( 𝐴 ∈ ℕ ∧ 𝑛 ∈ ( 2 ... 𝐴 ) ) → ( ( ( √ ‘ 𝑛 ) · ( 2 · ( ( √ ‘ 𝑛 ) − ( √ ‘ ( 𝑛 − 1 ) ) ) ) ) · ( √ ‘ ( 𝑛 − 1 ) ) ) = ( ( ( √ ‘ 𝑛 ) · ( √ ‘ ( 𝑛 − 1 ) ) ) · ( 2 · ( ( √ ‘ 𝑛 ) − ( √ ‘ ( 𝑛 − 1 ) ) ) ) ) )
81 77 78 80 3brtr3d ⊢ ( ( 𝐴 ∈ ℕ ∧ 𝑛 ∈ ( 2 ... 𝐴 ) ) → ( √ ‘ ( 𝑛 − 1 ) ) ≤ ( ( ( √ ‘ 𝑛 ) · ( √ ‘ ( 𝑛 − 1 ) ) ) · ( 2 · ( ( √ ‘ 𝑛 ) − ( √ ‘ ( 𝑛 − 1 ) ) ) ) ) )
82 remsqsqrt ⊢ ( ( 𝑛 ∈ ℝ ∧ 0 ≤ 𝑛 ) → ( ( √ ‘ 𝑛 ) · ( √ ‘ 𝑛 ) ) = 𝑛 )
83 26 46 82 syl2anc ⊢ ( ( 𝐴 ∈ ℕ ∧ 𝑛 ∈ ( 2 ... 𝐴 ) ) → ( ( √ ‘ 𝑛 ) · ( √ ‘ 𝑛 ) ) = 𝑛 )
84 remsqsqrt ⊢ ( ( ( 𝑛 − 1 ) ∈ ℝ ∧ 0 ≤ ( 𝑛 − 1 ) ) → ( ( √ ‘ ( 𝑛 − 1 ) ) · ( √ ‘ ( 𝑛 − 1 ) ) ) = ( 𝑛 − 1 ) )
85 28 36 84 syl2anc ⊢ ( ( 𝐴 ∈ ℕ ∧ 𝑛 ∈ ( 2 ... 𝐴 ) ) → ( ( √ ‘ ( 𝑛 − 1 ) ) · ( √ ‘ ( 𝑛 − 1 ) ) ) = ( 𝑛 − 1 ) )
86 83 85 oveq12d ⊢ ( ( 𝐴 ∈ ℕ ∧ 𝑛 ∈ ( 2 ... 𝐴 ) ) → ( ( ( √ ‘ 𝑛 ) · ( √ ‘ 𝑛 ) ) · ( ( √ ‘ ( 𝑛 − 1 ) ) · ( √ ‘ ( 𝑛 − 1 ) ) ) ) = ( 𝑛 · ( 𝑛 − 1 ) ) )
87 52 52 61 61 mul4d ⊢ ( ( 𝐴 ∈ ℕ ∧ 𝑛 ∈ ( 2 ... 𝐴 ) ) → ( ( ( √ ‘ 𝑛 ) · ( √ ‘ 𝑛 ) ) · ( ( √ ‘ ( 𝑛 − 1 ) ) · ( √ ‘ ( 𝑛 − 1 ) ) ) ) = ( ( ( √ ‘ 𝑛 ) · ( √ ‘ ( 𝑛 − 1 ) ) ) · ( ( √ ‘ 𝑛 ) · ( √ ‘ ( 𝑛 − 1 ) ) ) ) )
88 86 87 eqtr3d ⊢ ( ( 𝐴 ∈ ℕ ∧ 𝑛 ∈ ( 2 ... 𝐴 ) ) → ( 𝑛 · ( 𝑛 − 1 ) ) = ( ( ( √ ‘ 𝑛 ) · ( √ ‘ ( 𝑛 − 1 ) ) ) · ( ( √ ‘ 𝑛 ) · ( √ ‘ ( 𝑛 − 1 ) ) ) ) )
89 16 rpcnne0d ⊢ ( ( 𝐴 ∈ ℕ ∧ 𝑛 ∈ ( 2 ... 𝐴 ) ) → ( ( √ ‘ ( 𝑛 − 1 ) ) ∈ ℂ ∧ ( √ ‘ ( 𝑛 − 1 ) ) ≠ 0 ) )
90 19 rpcnne0d ⊢ ( ( 𝐴 ∈ ℕ ∧ 𝑛 ∈ ( 2 ... 𝐴 ) ) → ( ( √ ‘ 𝑛 ) ∈ ℂ ∧ ( √ ‘ 𝑛 ) ≠ 0 ) )
91 divsubdiv ⊢ ( ( ( 2 ∈ ℂ ∧ 2 ∈ ℂ ) ∧ ( ( ( √ ‘ ( 𝑛 − 1 ) ) ∈ ℂ ∧ ( √ ‘ ( 𝑛 − 1 ) ) ≠ 0 ) ∧ ( ( √ ‘ 𝑛 ) ∈ ℂ ∧ ( √ ‘ 𝑛 ) ≠ 0 ) ) ) → ( ( 2 / ( √ ‘ ( 𝑛 − 1 ) ) ) − ( 2 / ( √ ‘ 𝑛 ) ) ) = ( ( ( 2 · ( √ ‘ 𝑛 ) ) − ( 2 · ( √ ‘ ( 𝑛 − 1 ) ) ) ) / ( ( √ ‘ ( 𝑛 − 1 ) ) · ( √ ‘ 𝑛 ) ) ) )
92 68 68 89 90 91 syl22anc ⊢ ( ( 𝐴 ∈ ℕ ∧ 𝑛 ∈ ( 2 ... 𝐴 ) ) → ( ( 2 / ( √ ‘ ( 𝑛 − 1 ) ) ) − ( 2 / ( √ ‘ 𝑛 ) ) ) = ( ( ( 2 · ( √ ‘ 𝑛 ) ) − ( 2 · ( √ ‘ ( 𝑛 − 1 ) ) ) ) / ( ( √ ‘ ( 𝑛 − 1 ) ) · ( √ ‘ 𝑛 ) ) ) )
93 68 52 61 subdid ⊢ ( ( 𝐴 ∈ ℕ ∧ 𝑛 ∈ ( 2 ... 𝐴 ) ) → ( 2 · ( ( √ ‘ 𝑛 ) − ( √ ‘ ( 𝑛 − 1 ) ) ) ) = ( ( 2 · ( √ ‘ 𝑛 ) ) − ( 2 · ( √ ‘ ( 𝑛 − 1 ) ) ) ) )
94 52 61 mulcomd ⊢ ( ( 𝐴 ∈ ℕ ∧ 𝑛 ∈ ( 2 ... 𝐴 ) ) → ( ( √ ‘ 𝑛 ) · ( √ ‘ ( 𝑛 − 1 ) ) ) = ( ( √ ‘ ( 𝑛 − 1 ) ) · ( √ ‘ 𝑛 ) ) )
95 93 94 oveq12d ⊢ ( ( 𝐴 ∈ ℕ ∧ 𝑛 ∈ ( 2 ... 𝐴 ) ) → ( ( 2 · ( ( √ ‘ 𝑛 ) − ( √ ‘ ( 𝑛 − 1 ) ) ) ) / ( ( √ ‘ 𝑛 ) · ( √ ‘ ( 𝑛 − 1 ) ) ) ) = ( ( ( 2 · ( √ ‘ 𝑛 ) ) − ( 2 · ( √ ‘ ( 𝑛 − 1 ) ) ) ) / ( ( √ ‘ ( 𝑛 − 1 ) ) · ( √ ‘ 𝑛 ) ) ) )
96 92 95 eqtr4d ⊢ ( ( 𝐴 ∈ ℕ ∧ 𝑛 ∈ ( 2 ... 𝐴 ) ) → ( ( 2 / ( √ ‘ ( 𝑛 − 1 ) ) ) − ( 2 / ( √ ‘ 𝑛 ) ) ) = ( ( 2 · ( ( √ ‘ 𝑛 ) − ( √ ‘ ( 𝑛 − 1 ) ) ) ) / ( ( √ ‘ 𝑛 ) · ( √ ‘ ( 𝑛 − 1 ) ) ) ) )
97 88 96 oveq12d ⊢ ( ( 𝐴 ∈ ℕ ∧ 𝑛 ∈ ( 2 ... 𝐴 ) ) → ( ( 𝑛 · ( 𝑛 − 1 ) ) · ( ( 2 / ( √ ‘ ( 𝑛 − 1 ) ) ) − ( 2 / ( √ ‘ 𝑛 ) ) ) ) = ( ( ( ( √ ‘ 𝑛 ) · ( √ ‘ ( 𝑛 − 1 ) ) ) · ( ( √ ‘ 𝑛 ) · ( √ ‘ ( 𝑛 − 1 ) ) ) ) · ( ( 2 · ( ( √ ‘ 𝑛 ) − ( √ ‘ ( 𝑛 − 1 ) ) ) ) / ( ( √ ‘ 𝑛 ) · ( √ ‘ ( 𝑛 − 1 ) ) ) ) ) )
98 52 61 mulcld ⊢ ( ( 𝐴 ∈ ℕ ∧ 𝑛 ∈ ( 2 ... 𝐴 ) ) → ( ( √ ‘ 𝑛 ) · ( √ ‘ ( 𝑛 − 1 ) ) ) ∈ ℂ )
99 19 16 rpmulcld ⊢ ( ( 𝐴 ∈ ℕ ∧ 𝑛 ∈ ( 2 ... 𝐴 ) ) → ( ( √ ‘ 𝑛 ) · ( √ ‘ ( 𝑛 − 1 ) ) ) ∈ ℝ+ )
100 74 99 rerpdivcld ⊢ ( ( 𝐴 ∈ ℕ ∧ 𝑛 ∈ ( 2 ... 𝐴 ) ) → ( ( 2 · ( ( √ ‘ 𝑛 ) − ( √ ‘ ( 𝑛 − 1 ) ) ) ) / ( ( √ ‘ 𝑛 ) · ( √ ‘ ( 𝑛 − 1 ) ) ) ) ∈ ℝ )
101 100 recnd ⊢ ( ( 𝐴 ∈ ℕ ∧ 𝑛 ∈ ( 2 ... 𝐴 ) ) → ( ( 2 · ( ( √ ‘ 𝑛 ) − ( √ ‘ ( 𝑛 − 1 ) ) ) ) / ( ( √ ‘ 𝑛 ) · ( √ ‘ ( 𝑛 − 1 ) ) ) ) ∈ ℂ )
102 98 98 101 mulassd ⊢ ( ( 𝐴 ∈ ℕ ∧ 𝑛 ∈ ( 2 ... 𝐴 ) ) → ( ( ( ( √ ‘ 𝑛 ) · ( √ ‘ ( 𝑛 − 1 ) ) ) · ( ( √ ‘ 𝑛 ) · ( √ ‘ ( 𝑛 − 1 ) ) ) ) · ( ( 2 · ( ( √ ‘ 𝑛 ) − ( √ ‘ ( 𝑛 − 1 ) ) ) ) / ( ( √ ‘ 𝑛 ) · ( √ ‘ ( 𝑛 − 1 ) ) ) ) ) = ( ( ( √ ‘ 𝑛 ) · ( √ ‘ ( 𝑛 − 1 ) ) ) · ( ( ( √ ‘ 𝑛 ) · ( √ ‘ ( 𝑛 − 1 ) ) ) · ( ( 2 · ( ( √ ‘ 𝑛 ) − ( √ ‘ ( 𝑛 − 1 ) ) ) ) / ( ( √ ‘ 𝑛 ) · ( √ ‘ ( 𝑛 − 1 ) ) ) ) ) ) )
103 99 rpne0d ⊢ ( ( 𝐴 ∈ ℕ ∧ 𝑛 ∈ ( 2 ... 𝐴 ) ) → ( ( √ ‘ 𝑛 ) · ( √ ‘ ( 𝑛 − 1 ) ) ) ≠ 0 )
104 79 98 103 divcan2d ⊢ ( ( 𝐴 ∈ ℕ ∧ 𝑛 ∈ ( 2 ... 𝐴 ) ) → ( ( ( √ ‘ 𝑛 ) · ( √ ‘ ( 𝑛 − 1 ) ) ) · ( ( 2 · ( ( √ ‘ 𝑛 ) − ( √ ‘ ( 𝑛 − 1 ) ) ) ) / ( ( √ ‘ 𝑛 ) · ( √ ‘ ( 𝑛 − 1 ) ) ) ) ) = ( 2 · ( ( √ ‘ 𝑛 ) − ( √ ‘ ( 𝑛 − 1 ) ) ) ) )
105 104 oveq2d ⊢ ( ( 𝐴 ∈ ℕ ∧ 𝑛 ∈ ( 2 ... 𝐴 ) ) → ( ( ( √ ‘ 𝑛 ) · ( √ ‘ ( 𝑛 − 1 ) ) ) · ( ( ( √ ‘ 𝑛 ) · ( √ ‘ ( 𝑛 − 1 ) ) ) · ( ( 2 · ( ( √ ‘ 𝑛 ) − ( √ ‘ ( 𝑛 − 1 ) ) ) ) / ( ( √ ‘ 𝑛 ) · ( √ ‘ ( 𝑛 − 1 ) ) ) ) ) ) = ( ( ( √ ‘ 𝑛 ) · ( √ ‘ ( 𝑛 − 1 ) ) ) · ( 2 · ( ( √ ‘ 𝑛 ) − ( √ ‘ ( 𝑛 − 1 ) ) ) ) ) )
106 97 102 105 3eqtrd ⊢ ( ( 𝐴 ∈ ℕ ∧ 𝑛 ∈ ( 2 ... 𝐴 ) ) → ( ( 𝑛 · ( 𝑛 − 1 ) ) · ( ( 2 / ( √ ‘ ( 𝑛 − 1 ) ) ) − ( 2 / ( √ ‘ 𝑛 ) ) ) ) = ( ( ( √ ‘ 𝑛 ) · ( √ ‘ ( 𝑛 − 1 ) ) ) · ( 2 · ( ( √ ‘ 𝑛 ) − ( √ ‘ ( 𝑛 − 1 ) ) ) ) ) )
107 81 106 breqtrrd ⊢ ( ( 𝐴 ∈ ℕ ∧ 𝑛 ∈ ( 2 ... 𝐴 ) ) → ( √ ‘ ( 𝑛 − 1 ) ) ≤ ( ( 𝑛 · ( 𝑛 − 1 ) ) · ( ( 2 / ( √ ‘ ( 𝑛 − 1 ) ) ) − ( 2 / ( √ ‘ 𝑛 ) ) ) ) )
108 7 25 30 39 107 letrd ⊢ ( ( 𝐴 ∈ ℕ ∧ 𝑛 ∈ ( 2 ... 𝐴 ) ) → ( log ‘ 𝑛 ) ≤ ( ( 𝑛 · ( 𝑛 − 1 ) ) · ( ( 2 / ( √ ‘ ( 𝑛 − 1 ) ) ) − ( 2 / ( √ ‘ 𝑛 ) ) ) ) )
109 11 nngt0d ⊢ ( ( 𝐴 ∈ ℕ ∧ 𝑛 ∈ ( 2 ... 𝐴 ) ) → 0 < ( 𝑛 · ( 𝑛 − 1 ) ) )
110 ledivmul ⊢ ( ( ( log ‘ 𝑛 ) ∈ ℝ ∧ ( ( 2 / ( √ ‘ ( 𝑛 − 1 ) ) ) − ( 2 / ( √ ‘ 𝑛 ) ) ) ∈ ℝ ∧ ( ( 𝑛 · ( 𝑛 − 1 ) ) ∈ ℝ ∧ 0 < ( 𝑛 · ( 𝑛 − 1 ) ) ) ) → ( ( ( log ‘ 𝑛 ) / ( 𝑛 · ( 𝑛 − 1 ) ) ) ≤ ( ( 2 / ( √ ‘ ( 𝑛 − 1 ) ) ) − ( 2 / ( √ ‘ 𝑛 ) ) ) ↔ ( log ‘ 𝑛 ) ≤ ( ( 𝑛 · ( 𝑛 − 1 ) ) · ( ( 2 / ( √ ‘ ( 𝑛 − 1 ) ) ) − ( 2 / ( √ ‘ 𝑛 ) ) ) ) ) )
111 7 22 29 109 110 syl112anc ⊢ ( ( 𝐴 ∈ ℕ ∧ 𝑛 ∈ ( 2 ... 𝐴 ) ) → ( ( ( log ‘ 𝑛 ) / ( 𝑛 · ( 𝑛 − 1 ) ) ) ≤ ( ( 2 / ( √ ‘ ( 𝑛 − 1 ) ) ) − ( 2 / ( √ ‘ 𝑛 ) ) ) ↔ ( log ‘ 𝑛 ) ≤ ( ( 𝑛 · ( 𝑛 − 1 ) ) · ( ( 2 / ( √ ‘ ( 𝑛 − 1 ) ) ) − ( 2 / ( √ ‘ 𝑛 ) ) ) ) ) )
112 108 111 mpbird ⊢ ( ( 𝐴 ∈ ℕ ∧ 𝑛 ∈ ( 2 ... 𝐴 ) ) → ( ( log ‘ 𝑛 ) / ( 𝑛 · ( 𝑛 − 1 ) ) ) ≤ ( ( 2 / ( √ ‘ ( 𝑛 − 1 ) ) ) − ( 2 / ( √ ‘ 𝑛 ) ) ) )
113 1 12 22 112 fsumle ⊢ ( 𝐴 ∈ ℕ → Σ 𝑛 ∈ ( 2 ... 𝐴 ) ( ( log ‘ 𝑛 ) / ( 𝑛 · ( 𝑛 − 1 ) ) ) ≤ Σ 𝑛 ∈ ( 2 ... 𝐴 ) ( ( 2 / ( √ ‘ ( 𝑛 − 1 ) ) ) − ( 2 / ( √ ‘ 𝑛 ) ) ) )
114 fvoveq1 ⊢ ( 𝑘 = 𝑛 → ( √ ‘ ( 𝑘 − 1 ) ) = ( √ ‘ ( 𝑛 − 1 ) ) )
115 114 oveq2d ⊢ ( 𝑘 = 𝑛 → ( 2 / ( √ ‘ ( 𝑘 − 1 ) ) ) = ( 2 / ( √ ‘ ( 𝑛 − 1 ) ) ) )
116 fvoveq1 ⊢ ( 𝑘 = ( 𝑛 + 1 ) → ( √ ‘ ( 𝑘 − 1 ) ) = ( √ ‘ ( ( 𝑛 + 1 ) − 1 ) ) )
117 116 oveq2d ⊢ ( 𝑘 = ( 𝑛 + 1 ) → ( 2 / ( √ ‘ ( 𝑘 − 1 ) ) ) = ( 2 / ( √ ‘ ( ( 𝑛 + 1 ) − 1 ) ) ) )
118 oveq1 ⊢ ( 𝑘 = 2 → ( 𝑘 − 1 ) = ( 2 − 1 ) )
119 2m1e1 ⊢ ( 2 − 1 ) = 1
120 118 119 eqtrdi ⊢ ( 𝑘 = 2 → ( 𝑘 − 1 ) = 1 )
121 120 fveq2d ⊢ ( 𝑘 = 2 → ( √ ‘ ( 𝑘 − 1 ) ) = ( √ ‘ 1 ) )
122 sqrt1 ⊢ ( √ ‘ 1 ) = 1
123 121 122 eqtrdi ⊢ ( 𝑘 = 2 → ( √ ‘ ( 𝑘 − 1 ) ) = 1 )
124 123 oveq2d ⊢ ( 𝑘 = 2 → ( 2 / ( √ ‘ ( 𝑘 − 1 ) ) ) = ( 2 / 1 ) )
125 67 div1i ⊢ ( 2 / 1 ) = 2
126 124 125 eqtrdi ⊢ ( 𝑘 = 2 → ( 2 / ( √ ‘ ( 𝑘 − 1 ) ) ) = 2 )
127 fvoveq1 ⊢ ( 𝑘 = ( 𝐴 + 1 ) → ( √ ‘ ( 𝑘 − 1 ) ) = ( √ ‘ ( ( 𝐴 + 1 ) − 1 ) ) )
128 127 oveq2d ⊢ ( 𝑘 = ( 𝐴 + 1 ) → ( 2 / ( √ ‘ ( 𝑘 − 1 ) ) ) = ( 2 / ( √ ‘ ( ( 𝐴 + 1 ) − 1 ) ) ) )
129 nnz ⊢ ( 𝐴 ∈ ℕ → 𝐴 ∈ ℤ )
130 eluzp1p1 ⊢ ( 𝐴 ∈ ( ℤ≥ ‘ 1 ) → ( 𝐴 + 1 ) ∈ ( ℤ≥ ‘ ( 1 + 1 ) ) )
131 nnuz ⊢ ℕ = ( ℤ≥ ‘ 1 )
132 130 131 eleq2s ⊢ ( 𝐴 ∈ ℕ → ( 𝐴 + 1 ) ∈ ( ℤ≥ ‘ ( 1 + 1 ) ) )
133 df-2 ⊢ 2 = ( 1 + 1 )
134 133 fveq2i ⊢ ( ℤ≥ ‘ 2 ) = ( ℤ≥ ‘ ( 1 + 1 ) )
135 132 134 eleqtrrdi ⊢ ( 𝐴 ∈ ℕ → ( 𝐴 + 1 ) ∈ ( ℤ≥ ‘ 2 ) )
136 elfzuz ⊢ ( 𝑘 ∈ ( 2 ... ( 𝐴 + 1 ) ) → 𝑘 ∈ ( ℤ≥ ‘ 2 ) )
137 uz2m1nn ⊢ ( 𝑘 ∈ ( ℤ≥ ‘ 2 ) → ( 𝑘 − 1 ) ∈ ℕ )
138 136 137 syl ⊢ ( 𝑘 ∈ ( 2 ... ( 𝐴 + 1 ) ) → ( 𝑘 − 1 ) ∈ ℕ )
139 138 adantl ⊢ ( ( 𝐴 ∈ ℕ ∧ 𝑘 ∈ ( 2 ... ( 𝐴 + 1 ) ) ) → ( 𝑘 − 1 ) ∈ ℕ )
140 139 nnrpd ⊢ ( ( 𝐴 ∈ ℕ ∧ 𝑘 ∈ ( 2 ... ( 𝐴 + 1 ) ) ) → ( 𝑘 − 1 ) ∈ ℝ+ )
141 140 rpsqrtcld ⊢ ( ( 𝐴 ∈ ℕ ∧ 𝑘 ∈ ( 2 ... ( 𝐴 + 1 ) ) ) → ( √ ‘ ( 𝑘 − 1 ) ) ∈ ℝ+ )
142 rerpdivcl ⊢ ( ( 2 ∈ ℝ ∧ ( √ ‘ ( 𝑘 − 1 ) ) ∈ ℝ+ ) → ( 2 / ( √ ‘ ( 𝑘 − 1 ) ) ) ∈ ℝ )
143 14 141 142 sylancr ⊢ ( ( 𝐴 ∈ ℕ ∧ 𝑘 ∈ ( 2 ... ( 𝐴 + 1 ) ) ) → ( 2 / ( √ ‘ ( 𝑘 − 1 ) ) ) ∈ ℝ )
144 143 recnd ⊢ ( ( 𝐴 ∈ ℕ ∧ 𝑘 ∈ ( 2 ... ( 𝐴 + 1 ) ) ) → ( 2 / ( √ ‘ ( 𝑘 − 1 ) ) ) ∈ ℂ )
145 115 117 126 128 129 135 144 telfsum ⊢ ( 𝐴 ∈ ℕ → Σ 𝑛 ∈ ( 2 ... 𝐴 ) ( ( 2 / ( √ ‘ ( 𝑛 − 1 ) ) ) − ( 2 / ( √ ‘ ( ( 𝑛 + 1 ) − 1 ) ) ) ) = ( 2 − ( 2 / ( √ ‘ ( ( 𝐴 + 1 ) − 1 ) ) ) ) )
146 pncan ⊢ ( ( 𝑛 ∈ ℂ ∧ 1 ∈ ℂ ) → ( ( 𝑛 + 1 ) − 1 ) = 𝑛 )
147 31 32 146 sylancl ⊢ ( ( 𝐴 ∈ ℕ ∧ 𝑛 ∈ ( 2 ... 𝐴 ) ) → ( ( 𝑛 + 1 ) − 1 ) = 𝑛 )
148 147 fveq2d ⊢ ( ( 𝐴 ∈ ℕ ∧ 𝑛 ∈ ( 2 ... 𝐴 ) ) → ( √ ‘ ( ( 𝑛 + 1 ) − 1 ) ) = ( √ ‘ 𝑛 ) )
149 148 oveq2d ⊢ ( ( 𝐴 ∈ ℕ ∧ 𝑛 ∈ ( 2 ... 𝐴 ) ) → ( 2 / ( √ ‘ ( ( 𝑛 + 1 ) − 1 ) ) ) = ( 2 / ( √ ‘ 𝑛 ) ) )
150 149 oveq2d ⊢ ( ( 𝐴 ∈ ℕ ∧ 𝑛 ∈ ( 2 ... 𝐴 ) ) → ( ( 2 / ( √ ‘ ( 𝑛 − 1 ) ) ) − ( 2 / ( √ ‘ ( ( 𝑛 + 1 ) − 1 ) ) ) ) = ( ( 2 / ( √ ‘ ( 𝑛 − 1 ) ) ) − ( 2 / ( √ ‘ 𝑛 ) ) ) )
151 150 sumeq2dv ⊢ ( 𝐴 ∈ ℕ → Σ 𝑛 ∈ ( 2 ... 𝐴 ) ( ( 2 / ( √ ‘ ( 𝑛 − 1 ) ) ) − ( 2 / ( √ ‘ ( ( 𝑛 + 1 ) − 1 ) ) ) ) = Σ 𝑛 ∈ ( 2 ... 𝐴 ) ( ( 2 / ( √ ‘ ( 𝑛 − 1 ) ) ) − ( 2 / ( √ ‘ 𝑛 ) ) ) )
152 nncn ⊢ ( 𝐴 ∈ ℕ → 𝐴 ∈ ℂ )
153 pncan ⊢ ( ( 𝐴 ∈ ℂ ∧ 1 ∈ ℂ ) → ( ( 𝐴 + 1 ) − 1 ) = 𝐴 )
154 152 32 153 sylancl ⊢ ( 𝐴 ∈ ℕ → ( ( 𝐴 + 1 ) − 1 ) = 𝐴 )
155 154 fveq2d ⊢ ( 𝐴 ∈ ℕ → ( √ ‘ ( ( 𝐴 + 1 ) − 1 ) ) = ( √ ‘ 𝐴 ) )
156 155 oveq2d ⊢ ( 𝐴 ∈ ℕ → ( 2 / ( √ ‘ ( ( 𝐴 + 1 ) − 1 ) ) ) = ( 2 / ( √ ‘ 𝐴 ) ) )
157 156 oveq2d ⊢ ( 𝐴 ∈ ℕ → ( 2 − ( 2 / ( √ ‘ ( ( 𝐴 + 1 ) − 1 ) ) ) ) = ( 2 − ( 2 / ( √ ‘ 𝐴 ) ) ) )
158 145 151 157 3eqtr3d ⊢ ( 𝐴 ∈ ℕ → Σ 𝑛 ∈ ( 2 ... 𝐴 ) ( ( 2 / ( √ ‘ ( 𝑛 − 1 ) ) ) − ( 2 / ( √ ‘ 𝑛 ) ) ) = ( 2 − ( 2 / ( √ ‘ 𝐴 ) ) ) )
159 2rp ⊢ 2 ∈ ℝ+
160 nnrp ⊢ ( 𝐴 ∈ ℕ → 𝐴 ∈ ℝ+ )
161 160 rpsqrtcld ⊢ ( 𝐴 ∈ ℕ → ( √ ‘ 𝐴 ) ∈ ℝ+ )
162 rpdivcl ⊢ ( ( 2 ∈ ℝ+ ∧ ( √ ‘ 𝐴 ) ∈ ℝ+ ) → ( 2 / ( √ ‘ 𝐴 ) ) ∈ ℝ+ )
163 159 161 162 sylancr ⊢ ( 𝐴 ∈ ℕ → ( 2 / ( √ ‘ 𝐴 ) ) ∈ ℝ+ )
164 163 rpge0d ⊢ ( 𝐴 ∈ ℕ → 0 ≤ ( 2 / ( √ ‘ 𝐴 ) ) )
165 163 rpred ⊢ ( 𝐴 ∈ ℕ → ( 2 / ( √ ‘ 𝐴 ) ) ∈ ℝ )
166 subge02 ⊢ ( ( 2 ∈ ℝ ∧ ( 2 / ( √ ‘ 𝐴 ) ) ∈ ℝ ) → ( 0 ≤ ( 2 / ( √ ‘ 𝐴 ) ) ↔ ( 2 − ( 2 / ( √ ‘ 𝐴 ) ) ) ≤ 2 ) )
167 14 165 166 sylancr ⊢ ( 𝐴 ∈ ℕ → ( 0 ≤ ( 2 / ( √ ‘ 𝐴 ) ) ↔ ( 2 − ( 2 / ( √ ‘ 𝐴 ) ) ) ≤ 2 ) )
168 164 167 mpbid ⊢ ( 𝐴 ∈ ℕ → ( 2 − ( 2 / ( √ ‘ 𝐴 ) ) ) ≤ 2 )
169 158 168 eqbrtrd ⊢ ( 𝐴 ∈ ℕ → Σ 𝑛 ∈ ( 2 ... 𝐴 ) ( ( 2 / ( √ ‘ ( 𝑛 − 1 ) ) ) − ( 2 / ( √ ‘ 𝑛 ) ) ) ≤ 2 )
170 13 23 24 113 169 letrd ⊢ ( 𝐴 ∈ ℕ → Σ 𝑛 ∈ ( 2 ... 𝐴 ) ( ( log ‘ 𝑛 ) / ( 𝑛 · ( 𝑛 − 1 ) ) ) ≤ 2 )