Metamath Proof Explorer


Theorem faclim

Description: An infinite product expression relating to factorials. Originally due to Euler. (Contributed by Scott Fenton, 22-Nov-2017)

Ref Expression
Hypothesis faclim.1 ⊢ F = n ∈ ℕ ⟼ 1 + 1 n A 1 + A n
Assertion faclim ⊢ A ∈ ℕ 0 → seq 1 × F ⇝ A !

Proof

Step Hyp Ref Expression
1 faclim.1 ⊢ F = n ∈ ℕ ⟼ 1 + 1 n A 1 + A n
2 seqeq3 ⊢ F = n ∈ ℕ ⟼ 1 + 1 n A 1 + A n → seq 1 × F = seq 1 × n ∈ ℕ ⟼ 1 + 1 n A 1 + A n
3 1 2 ax-mp ⊢ seq 1 × F = seq 1 × n ∈ ℕ ⟼ 1 + 1 n A 1 + A n
4 oveq2 ⊢ a = 0 → 1 + 1 n a = 1 + 1 n 0
5 oveq1 ⊢ a = 0 → a n = 0 n
6 5 oveq2d ⊢ a = 0 → 1 + a n = 1 + 0 n
7 4 6 oveq12d ⊢ a = 0 → 1 + 1 n a 1 + a n = 1 + 1 n 0 1 + 0 n
8 7 mpteq2dv ⊢ a = 0 → n ∈ ℕ ⟼ 1 + 1 n a 1 + a n = n ∈ ℕ ⟼ 1 + 1 n 0 1 + 0 n
9 8 seqeq3d ⊢ a = 0 → seq 1 × n ∈ ℕ ⟼ 1 + 1 n a 1 + a n = seq 1 × n ∈ ℕ ⟼ 1 + 1 n 0 1 + 0 n
10 fveq2 ⊢ a = 0 → a ! = 0 !
11 fac0 ⊢ 0 ! = 1
12 10 11 eqtrdi ⊢ a = 0 → a ! = 1
13 9 12 breq12d ⊢ a = 0 → seq 1 × n ∈ ℕ ⟼ 1 + 1 n a 1 + a n ⇝ a ! ↔ seq 1 × n ∈ ℕ ⟼ 1 + 1 n 0 1 + 0 n ⇝ 1
14 oveq2 ⊢ a = m → 1 + 1 n a = 1 + 1 n m
15 oveq1 ⊢ a = m → a n = m n
16 15 oveq2d ⊢ a = m → 1 + a n = 1 + m n
17 14 16 oveq12d ⊢ a = m → 1 + 1 n a 1 + a n = 1 + 1 n m 1 + m n
18 17 mpteq2dv ⊢ a = m → n ∈ ℕ ⟼ 1 + 1 n a 1 + a n = n ∈ ℕ ⟼ 1 + 1 n m 1 + m n
19 18 seqeq3d ⊢ a = m → seq 1 × n ∈ ℕ ⟼ 1 + 1 n a 1 + a n = seq 1 × n ∈ ℕ ⟼ 1 + 1 n m 1 + m n
20 fveq2 ⊢ a = m → a ! = m !
21 19 20 breq12d ⊢ a = m → seq 1 × n ∈ ℕ ⟼ 1 + 1 n a 1 + a n ⇝ a ! ↔ seq 1 × n ∈ ℕ ⟼ 1 + 1 n m 1 + m n ⇝ m !
22 oveq2 ⊢ a = m + 1 → 1 + 1 n a = 1 + 1 n m + 1
23 oveq1 ⊢ a = m + 1 → a n = m + 1 n
24 23 oveq2d ⊢ a = m + 1 → 1 + a n = 1 + m + 1 n
25 22 24 oveq12d ⊢ a = m + 1 → 1 + 1 n a 1 + a n = 1 + 1 n m + 1 1 + m + 1 n
26 25 mpteq2dv ⊢ a = m + 1 → n ∈ ℕ ⟼ 1 + 1 n a 1 + a n = n ∈ ℕ ⟼ 1 + 1 n m + 1 1 + m + 1 n
27 26 seqeq3d ⊢ a = m + 1 → seq 1 × n ∈ ℕ ⟼ 1 + 1 n a 1 + a n = seq 1 × n ∈ ℕ ⟼ 1 + 1 n m + 1 1 + m + 1 n
28 fveq2 ⊢ a = m + 1 → a ! = m + 1 !
29 27 28 breq12d ⊢ a = m + 1 → seq 1 × n ∈ ℕ ⟼ 1 + 1 n a 1 + a n ⇝ a ! ↔ seq 1 × n ∈ ℕ ⟼ 1 + 1 n m + 1 1 + m + 1 n ⇝ m + 1 !
30 oveq2 ⊢ a = A → 1 + 1 n a = 1 + 1 n A
31 oveq1 ⊢ a = A → a n = A n
32 31 oveq2d ⊢ a = A → 1 + a n = 1 + A n
33 30 32 oveq12d ⊢ a = A → 1 + 1 n a 1 + a n = 1 + 1 n A 1 + A n
34 33 mpteq2dv ⊢ a = A → n ∈ ℕ ⟼ 1 + 1 n a 1 + a n = n ∈ ℕ ⟼ 1 + 1 n A 1 + A n
35 34 seqeq3d ⊢ a = A → seq 1 × n ∈ ℕ ⟼ 1 + 1 n a 1 + a n = seq 1 × n ∈ ℕ ⟼ 1 + 1 n A 1 + A n
36 fveq2 ⊢ a = A → a ! = A !
37 35 36 breq12d ⊢ a = A → seq 1 × n ∈ ℕ ⟼ 1 + 1 n a 1 + a n ⇝ a ! ↔ seq 1 × n ∈ ℕ ⟼ 1 + 1 n A 1 + A n ⇝ A !
38 1red ⊢ n ∈ ℕ → 1 ∈ ℝ
39 nnrecre ⊢ n ∈ ℕ → 1 n ∈ ℝ
40 38 39 readdcld ⊢ n ∈ ℕ → 1 + 1 n ∈ ℝ
41 40 recnd ⊢ n ∈ ℕ → 1 + 1 n ∈ ℂ
42 41 exp0d ⊢ n ∈ ℕ → 1 + 1 n 0 = 1
43 nncn ⊢ n ∈ ℕ → n ∈ ℂ
44 nnne0 ⊢ n ∈ ℕ → n ≠ 0
45 43 44 div0d ⊢ n ∈ ℕ → 0 n = 0
46 45 oveq2d ⊢ n ∈ ℕ → 1 + 0 n = 1 + 0
47 1p0e1 ⊢ 1 + 0 = 1
48 46 47 eqtrdi ⊢ n ∈ ℕ → 1 + 0 n = 1
49 42 48 oveq12d ⊢ n ∈ ℕ → 1 + 1 n 0 1 + 0 n = 1 1
50 1div1e1 ⊢ 1 1 = 1
51 49 50 eqtrdi ⊢ n ∈ ℕ → 1 + 1 n 0 1 + 0 n = 1
52 51 mpteq2ia ⊢ n ∈ ℕ ⟼ 1 + 1 n 0 1 + 0 n = n ∈ ℕ ⟼ 1
53 fconstmpt ⊢ ℕ × 1 = n ∈ ℕ ⟼ 1
54 52 53 eqtr4i ⊢ n ∈ ℕ ⟼ 1 + 1 n 0 1 + 0 n = ℕ × 1
55 seqeq3 ⊢ n ∈ ℕ ⟼ 1 + 1 n 0 1 + 0 n = ℕ × 1 → seq 1 × n ∈ ℕ ⟼ 1 + 1 n 0 1 + 0 n = seq 1 × ℕ × 1
56 54 55 ax-mp ⊢ seq 1 × n ∈ ℕ ⟼ 1 + 1 n 0 1 + 0 n = seq 1 × ℕ × 1
57 nnuz ⊢ ℕ = ℤ ≥ 1
58 1zzd ⊢ ⊤ → 1 ∈ ℤ
59 57 58 climprod1 ⊢ ⊤ → seq 1 × ℕ × 1 ⇝ 1
60 59 mptru ⊢ seq 1 × ℕ × 1 ⇝ 1
61 56 60 eqbrtri ⊢ seq 1 × n ∈ ℕ ⟼ 1 + 1 n 0 1 + 0 n ⇝ 1
62 1zzd ⊢ m ∈ ℕ 0 ∧ seq 1 × n ∈ ℕ ⟼ 1 + 1 n m 1 + m n ⇝ m ! → 1 ∈ ℤ
63 simpr ⊢ m ∈ ℕ 0 ∧ seq 1 × n ∈ ℕ ⟼ 1 + 1 n m 1 + m n ⇝ m ! → seq 1 × n ∈ ℕ ⟼ 1 + 1 n m 1 + m n ⇝ m !
64 seqex ⊢ seq 1 × n ∈ ℕ ⟼ 1 + 1 n m + 1 1 + m + 1 n ∈ V
65 64 a1i ⊢ m ∈ ℕ 0 ∧ seq 1 × n ∈ ℕ ⟼ 1 + 1 n m 1 + m n ⇝ m ! → seq 1 × n ∈ ℕ ⟼ 1 + 1 n m + 1 1 + m + 1 n ∈ V
66 faclimlem2 ⊢ m ∈ ℕ 0 → seq 1 × n ∈ ℕ ⟼ 1 + m n ⁢ 1 + 1 n 1 + m + 1 n ⇝ m + 1
67 66 adantr ⊢ m ∈ ℕ 0 ∧ seq 1 × n ∈ ℕ ⟼ 1 + 1 n m 1 + m n ⇝ m ! → seq 1 × n ∈ ℕ ⟼ 1 + m n ⁢ 1 + 1 n 1 + m + 1 n ⇝ m + 1
68 elnnuz ⊢ a ∈ ℕ ↔ a ∈ ℤ ≥ 1
69 68 bilani ⊢ m ∈ ℕ 0 ∧ a ∈ ℕ → a ∈ ℤ ≥ 1
70 1rp ⊢ 1 ∈ ℝ +
71 70 a1i ⊢ m ∈ ℕ 0 ∧ n ∈ ℕ → 1 ∈ ℝ +
72 nnrp ⊢ n ∈ ℕ → n ∈ ℝ +
73 72 rpreccld ⊢ n ∈ ℕ → 1 n ∈ ℝ +
74 73 adantl ⊢ m ∈ ℕ 0 ∧ n ∈ ℕ → 1 n ∈ ℝ +
75 71 74 rpaddcld ⊢ m ∈ ℕ 0 ∧ n ∈ ℕ → 1 + 1 n ∈ ℝ +
76 nn0z ⊢ m ∈ ℕ 0 → m ∈ ℤ
77 76 adantr ⊢ m ∈ ℕ 0 ∧ n ∈ ℕ → m ∈ ℤ
78 75 77 rpexpcld ⊢ m ∈ ℕ 0 ∧ n ∈ ℕ → 1 + 1 n m ∈ ℝ +
79 1cnd ⊢ m ∈ ℕ 0 ∧ n ∈ ℕ → 1 ∈ ℂ
80 nn0nndivcl ⊢ m ∈ ℕ 0 ∧ n ∈ ℕ → m n ∈ ℝ
81 80 recnd ⊢ m ∈ ℕ 0 ∧ n ∈ ℕ → m n ∈ ℂ
82 79 81 addcomd ⊢ m ∈ ℕ 0 ∧ n ∈ ℕ → 1 + m n = m n + 1
83 nn0ge0div ⊢ m ∈ ℕ 0 ∧ n ∈ ℕ → 0 ≤ m n
84 80 83 ge0p1rpd ⊢ m ∈ ℕ 0 ∧ n ∈ ℕ → m n + 1 ∈ ℝ +
85 82 84 eqeltrd ⊢ m ∈ ℕ 0 ∧ n ∈ ℕ → 1 + m n ∈ ℝ +
86 78 85 rpdivcld ⊢ m ∈ ℕ 0 ∧ n ∈ ℕ → 1 + 1 n m 1 + m n ∈ ℝ +
87 86 rpcnd ⊢ m ∈ ℕ 0 ∧ n ∈ ℕ → 1 + 1 n m 1 + m n ∈ ℂ
88 87 fmpttd ⊢ m ∈ ℕ 0 → n ∈ ℕ ⟼ 1 + 1 n m 1 + m n : ℕ ⟶ ℂ
89 elfznn ⊢ b ∈ 1 … a → b ∈ ℕ
90 ffvelcdm ⊢ n ∈ ℕ ⟼ 1 + 1 n m 1 + m n : ℕ ⟶ ℂ ∧ b ∈ ℕ → n ∈ ℕ ⟼ 1 + 1 n m 1 + m n ⁡ b ∈ ℂ
91 88 89 90 syl2an ⊢ m ∈ ℕ 0 ∧ b ∈ 1 … a → n ∈ ℕ ⟼ 1 + 1 n m 1 + m n ⁡ b ∈ ℂ
92 91 adantlr ⊢ m ∈ ℕ 0 ∧ a ∈ ℕ ∧ b ∈ 1 … a → n ∈ ℕ ⟼ 1 + 1 n m 1 + m n ⁡ b ∈ ℂ
93 mulcl ⊢ b ∈ ℂ ∧ x ∈ ℂ → b ⁢ x ∈ ℂ
94 93 adantl ⊢ m ∈ ℕ 0 ∧ a ∈ ℕ ∧ b ∈ ℂ ∧ x ∈ ℂ → b ⁢ x ∈ ℂ
95 69 92 94 seqcl ⊢ m ∈ ℕ 0 ∧ a ∈ ℕ → seq 1 × n ∈ ℕ ⟼ 1 + 1 n m 1 + m n ⁡ a ∈ ℂ
96 95 adantlr ⊢ m ∈ ℕ 0 ∧ seq 1 × n ∈ ℕ ⟼ 1 + 1 n m 1 + m n ⇝ m ! ∧ a ∈ ℕ → seq 1 × n ∈ ℕ ⟼ 1 + 1 n m 1 + m n ⁡ a ∈ ℂ
97 85 75 rpmulcld ⊢ m ∈ ℕ 0 ∧ n ∈ ℕ → 1 + m n ⁢ 1 + 1 n ∈ ℝ +
98 nn0p1nn ⊢ m ∈ ℕ 0 → m + 1 ∈ ℕ
99 98 nnrpd ⊢ m ∈ ℕ 0 → m + 1 ∈ ℝ +
100 rpdivcl ⊢ m + 1 ∈ ℝ + ∧ n ∈ ℝ + → m + 1 n ∈ ℝ +
101 99 72 100 syl2an ⊢ m ∈ ℕ 0 ∧ n ∈ ℕ → m + 1 n ∈ ℝ +
102 71 101 rpaddcld ⊢ m ∈ ℕ 0 ∧ n ∈ ℕ → 1 + m + 1 n ∈ ℝ +
103 97 102 rpdivcld ⊢ m ∈ ℕ 0 ∧ n ∈ ℕ → 1 + m n ⁢ 1 + 1 n 1 + m + 1 n ∈ ℝ +
104 103 rpcnd ⊢ m ∈ ℕ 0 ∧ n ∈ ℕ → 1 + m n ⁢ 1 + 1 n 1 + m + 1 n ∈ ℂ
105 104 fmpttd ⊢ m ∈ ℕ 0 → n ∈ ℕ ⟼ 1 + m n ⁢ 1 + 1 n 1 + m + 1 n : ℕ ⟶ ℂ
106 ffvelcdm ⊢ n ∈ ℕ ⟼ 1 + m n ⁢ 1 + 1 n 1 + m + 1 n : ℕ ⟶ ℂ ∧ b ∈ ℕ → n ∈ ℕ ⟼ 1 + m n ⁢ 1 + 1 n 1 + m + 1 n ⁡ b ∈ ℂ
107 105 89 106 syl2an ⊢ m ∈ ℕ 0 ∧ b ∈ 1 … a → n ∈ ℕ ⟼ 1 + m n ⁢ 1 + 1 n 1 + m + 1 n ⁡ b ∈ ℂ
108 107 adantlr ⊢ m ∈ ℕ 0 ∧ a ∈ ℕ ∧ b ∈ 1 … a → n ∈ ℕ ⟼ 1 + m n ⁢ 1 + 1 n 1 + m + 1 n ⁡ b ∈ ℂ
109 69 108 94 seqcl ⊢ m ∈ ℕ 0 ∧ a ∈ ℕ → seq 1 × n ∈ ℕ ⟼ 1 + m n ⁢ 1 + 1 n 1 + m + 1 n ⁡ a ∈ ℂ
110 109 adantlr ⊢ m ∈ ℕ 0 ∧ seq 1 × n ∈ ℕ ⟼ 1 + 1 n m 1 + m n ⇝ m ! ∧ a ∈ ℕ → seq 1 × n ∈ ℕ ⟼ 1 + m n ⁢ 1 + 1 n 1 + m + 1 n ⁡ a ∈ ℂ
111 faclimlem3 ⊢ m ∈ ℕ 0 ∧ b ∈ ℕ → 1 + 1 b m + 1 1 + m + 1 b = 1 + 1 b m 1 + m b ⁢ 1 + m b ⁢ 1 + 1 b 1 + m + 1 b
112 oveq2 ⊢ n = b → 1 n = 1 b
113 112 oveq2d ⊢ n = b → 1 + 1 n = 1 + 1 b
114 113 oveq1d ⊢ n = b → 1 + 1 n m + 1 = 1 + 1 b m + 1
115 oveq2 ⊢ n = b → m + 1 n = m + 1 b
116 115 oveq2d ⊢ n = b → 1 + m + 1 n = 1 + m + 1 b
117 114 116 oveq12d ⊢ n = b → 1 + 1 n m + 1 1 + m + 1 n = 1 + 1 b m + 1 1 + m + 1 b
118 eqid ⊢ n ∈ ℕ ⟼ 1 + 1 n m + 1 1 + m + 1 n = n ∈ ℕ ⟼ 1 + 1 n m + 1 1 + m + 1 n
119 ovex ⊢ 1 + 1 b m + 1 1 + m + 1 b ∈ V
120 117 118 119 fvmpt ⊢ b ∈ ℕ → n ∈ ℕ ⟼ 1 + 1 n m + 1 1 + m + 1 n ⁡ b = 1 + 1 b m + 1 1 + m + 1 b
121 120 adantl ⊢ m ∈ ℕ 0 ∧ b ∈ ℕ → n ∈ ℕ ⟼ 1 + 1 n m + 1 1 + m + 1 n ⁡ b = 1 + 1 b m + 1 1 + m + 1 b
122 113 oveq1d ⊢ n = b → 1 + 1 n m = 1 + 1 b m
123 oveq2 ⊢ n = b → m n = m b
124 123 oveq2d ⊢ n = b → 1 + m n = 1 + m b
125 122 124 oveq12d ⊢ n = b → 1 + 1 n m 1 + m n = 1 + 1 b m 1 + m b
126 eqid ⊢ n ∈ ℕ ⟼ 1 + 1 n m 1 + m n = n ∈ ℕ ⟼ 1 + 1 n m 1 + m n
127 ovex ⊢ 1 + 1 b m 1 + m b ∈ V
128 125 126 127 fvmpt ⊢ b ∈ ℕ → n ∈ ℕ ⟼ 1 + 1 n m 1 + m n ⁡ b = 1 + 1 b m 1 + m b
129 124 113 oveq12d ⊢ n = b → 1 + m n ⁢ 1 + 1 n = 1 + m b ⁢ 1 + 1 b
130 129 116 oveq12d ⊢ n = b → 1 + m n ⁢ 1 + 1 n 1 + m + 1 n = 1 + m b ⁢ 1 + 1 b 1 + m + 1 b
131 eqid ⊢ n ∈ ℕ ⟼ 1 + m n ⁢ 1 + 1 n 1 + m + 1 n = n ∈ ℕ ⟼ 1 + m n ⁢ 1 + 1 n 1 + m + 1 n
132 ovex ⊢ 1 + m b ⁢ 1 + 1 b 1 + m + 1 b ∈ V
133 130 131 132 fvmpt ⊢ b ∈ ℕ → n ∈ ℕ ⟼ 1 + m n ⁢ 1 + 1 n 1 + m + 1 n ⁡ b = 1 + m b ⁢ 1 + 1 b 1 + m + 1 b
134 128 133 oveq12d ⊢ b ∈ ℕ → n ∈ ℕ ⟼ 1 + 1 n m 1 + m n ⁡ b ⁢ n ∈ ℕ ⟼ 1 + m n ⁢ 1 + 1 n 1 + m + 1 n ⁡ b = 1 + 1 b m 1 + m b ⁢ 1 + m b ⁢ 1 + 1 b 1 + m + 1 b
135 134 adantl ⊢ m ∈ ℕ 0 ∧ b ∈ ℕ → n ∈ ℕ ⟼ 1 + 1 n m 1 + m n ⁡ b ⁢ n ∈ ℕ ⟼ 1 + m n ⁢ 1 + 1 n 1 + m + 1 n ⁡ b = 1 + 1 b m 1 + m b ⁢ 1 + m b ⁢ 1 + 1 b 1 + m + 1 b
136 111 121 135 3eqtr4d ⊢ m ∈ ℕ 0 ∧ b ∈ ℕ → n ∈ ℕ ⟼ 1 + 1 n m + 1 1 + m + 1 n ⁡ b = n ∈ ℕ ⟼ 1 + 1 n m 1 + m n ⁡ b ⁢ n ∈ ℕ ⟼ 1 + m n ⁢ 1 + 1 n 1 + m + 1 n ⁡ b
137 89 136 sylan2 ⊢ m ∈ ℕ 0 ∧ b ∈ 1 … a → n ∈ ℕ ⟼ 1 + 1 n m + 1 1 + m + 1 n ⁡ b = n ∈ ℕ ⟼ 1 + 1 n m 1 + m n ⁡ b ⁢ n ∈ ℕ ⟼ 1 + m n ⁢ 1 + 1 n 1 + m + 1 n ⁡ b
138 137 adantlr ⊢ m ∈ ℕ 0 ∧ a ∈ ℕ ∧ b ∈ 1 … a → n ∈ ℕ ⟼ 1 + 1 n m + 1 1 + m + 1 n ⁡ b = n ∈ ℕ ⟼ 1 + 1 n m 1 + m n ⁡ b ⁢ n ∈ ℕ ⟼ 1 + m n ⁢ 1 + 1 n 1 + m + 1 n ⁡ b
139 69 92 108 138 prodfmul ⊢ m ∈ ℕ 0 ∧ a ∈ ℕ → seq 1 × n ∈ ℕ ⟼ 1 + 1 n m + 1 1 + m + 1 n ⁡ a = seq 1 × n ∈ ℕ ⟼ 1 + 1 n m 1 + m n ⁡ a ⁢ seq 1 × n ∈ ℕ ⟼ 1 + m n ⁢ 1 + 1 n 1 + m + 1 n ⁡ a
140 139 adantlr ⊢ m ∈ ℕ 0 ∧ seq 1 × n ∈ ℕ ⟼ 1 + 1 n m 1 + m n ⇝ m ! ∧ a ∈ ℕ → seq 1 × n ∈ ℕ ⟼ 1 + 1 n m + 1 1 + m + 1 n ⁡ a = seq 1 × n ∈ ℕ ⟼ 1 + 1 n m 1 + m n ⁡ a ⁢ seq 1 × n ∈ ℕ ⟼ 1 + m n ⁢ 1 + 1 n 1 + m + 1 n ⁡ a
141 57 62 63 65 67 96 110 140 climmul ⊢ m ∈ ℕ 0 ∧ seq 1 × n ∈ ℕ ⟼ 1 + 1 n m 1 + m n ⇝ m ! → seq 1 × n ∈ ℕ ⟼ 1 + 1 n m + 1 1 + m + 1 n ⇝ m ! ⁢ m + 1
142 facp1 ⊢ m ∈ ℕ 0 → m + 1 ! = m ! ⁢ m + 1
143 142 adantr ⊢ m ∈ ℕ 0 ∧ seq 1 × n ∈ ℕ ⟼ 1 + 1 n m 1 + m n ⇝ m ! → m + 1 ! = m ! ⁢ m + 1
144 141 143 breqtrrd ⊢ m ∈ ℕ 0 ∧ seq 1 × n ∈ ℕ ⟼ 1 + 1 n m 1 + m n ⇝ m ! → seq 1 × n ∈ ℕ ⟼ 1 + 1 n m + 1 1 + m + 1 n ⇝ m + 1 !
145 144 ex ⊢ m ∈ ℕ 0 → seq 1 × n ∈ ℕ ⟼ 1 + 1 n m 1 + m n ⇝ m ! → seq 1 × n ∈ ℕ ⟼ 1 + 1 n m + 1 1 + m + 1 n ⇝ m + 1 !
146 13 21 29 37 61 145 nn0ind ⊢ A ∈ ℕ 0 → seq 1 × n ∈ ℕ ⟼ 1 + 1 n A 1 + A n ⇝ A !
147 3 146 eqbrtrid ⊢ A ∈ ℕ 0 → seq 1 × F ⇝ A !