| fac(j) * fac(i - j) | (i - j) * fac(i - 1), fac(j) * fac(i - j) | j * fac(i - 1), fac(j - 1) * fac(i - j) | fac(i - 1), fac(j) * fac(i - 1 + j) | fac(i - 1), j < i, fac(j) * fac(i - j) | i * fac(i - 1), 0 < j, 0 ≤ j, 1 < i, 0 < i ⊦ fac(j) * fac(i - j) | fac(i) |
⊦ 0 < i → fac(i) = i * fac(i - 1)
Used terms: i