Let tn denote the nth triangular number. For which values of n does tn divide[Hint: Becaus...

Let tn denote the nth triangular number. For which values of n does tn divide

[Hint: Because , it suffices to determine those n satisfying 3n3 + 12n2 + 13n + 2 ≡ 0 (mod 2 · 3 · 5).]