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 mulid2d ( ( 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 )