⊦ (i + i0) * j = i * j + i0 * j
(j + 1) * (j + 1) = i0 + 1, 0 < i0, 0 ≤ i0, j * j ≤ i0, 0 < j, 2 * (2 + j) + j * (2 + j) ≤ i0 + 1 ⊦
Used terms: 2 + j, j, 2