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