| (i1 + 1) * (i1 + 1) * 4 < (2 + i1) * (2 + i1), (i1 + 1) * (i1 + 1) * 4 < 4 ^ i1 * 4, 4 ^ i1 * 4 ≤ (2 + i1) * (2 + i1), 0 ≤ i1, (i1 + 1) * (i1 + 1) < 4 ^ i1, 1 < i1, 0 < i1, ∀ i0. i→n(i0) < i→n(i1 + 1) → 4 ^ i0 ≤ (i0 + 1) * (i0 + 1) ∧ 0 < i0 ∧ 1 < i0 → false ⊦ |
(2 + i1) * (2 + i1) = i1 * i1 + 4 * i1 + 4, (i1 + 1) * (i1 + 1) * 4 < (2 + i1) * (2 + i1), (i1 + 1) * (i1 + 1) * 4 < 4 ^ i1 * 4, 4 ^ i1 * 4 ≤ (2 + i1) * (2 + i1), 0 ≤ i1, (i1 + 1) * (i1 + 1) < 4 ^ i1, 1 < i1, 0 < i1, ∀ i0. i→n(i0) < i→n(i1 + 1) → 4 ^ i0 ≤ (i0 + 1) * (i0 + 1) ∧ 0 < i0 ∧ 1 < i0 → false ⊦
(i1 + 1) * (i1 + 1) * 4 < (2 + i1) * (2 + i1), (i1 + 1) * (i1 + 1) * 4 < 4 ^ i1 * 4, 4 ^ i1 * 4 ≤ (2 + i1) * (2 + i1), 0 ≤ i1, (i1 + 1) * (i1 + 1) < 4 ^ i1, 1 < i1, 0 < i1, ∀ i0. i→n(i0) < i→n(i1 + 1) → 4 ^ i0 ≤ (i0 + 1) * (i0 + 1) ∧ 0 < i0 ∧ 1 < i0 → false ⊦ (2 + i1) * (2 + i1) = i1 * i1 + 4 * i1 + 4
Used formulas: (2 + i1) * (2 + i1) = i1 * i1 + 4 * i1 + 4