(j * (j + 1)) / 2 ≤ j, 0 ≤ j, 2 ≤ j, 0 < j ⊦
Used simplifier rules: forward-le: ⊦ i ≤ j ∧ 0 < i → 0 < j; (forward) from specification int-abs%lels: ⊦ ¬ i < j ↔ j ≤ i; from specification int-abs