| 0 ≤ j - 1 ∧ j - 1 ≤ i, 0 ≤ j ∧ j ≤ i, j ≤ i, 0 < j, 0 < i, fac(i - j) * fac(j) | fac(i), 0 ≤ j, 0 ≤ i, fac(i + 1 - j) * fac(j - 1) | fac(i) ⊦ fac(i) / (fac(i - j) * fac(j)) * j = fac(i) / (fac(i - (j - 1)) * fac(j - 1)) * (i + 1 - j) |
⊦ i | j ↔ (∃ i0. i * i0 = j)
0 ≤ j - 1 ∧ j - 1 ≤ i, 0 ≤ j ∧ j ≤ i, j ≤ i, 0 < j, 0 < i, ∃ i0. (fac(i - j) * fac(j)) * i0 = fac(i), 0 ≤ j, 0 ≤ i, fac(i + 1 - j) * fac(j - 1) | fac(i) ⊦ fac(i) / (fac(i - j) * fac(j)) * j = fac(i) / (fac(i - (j - 1)) * fac(j - 1)) * (i + 1 - j)
Used terms: fac(i), fac(i - j) * fac(j)