Subsequence A005318(t_n), where t_n is the n-th triangular number (A000217).

A206239

Subsequence A005318(t_n), where t_n is the n-th triangular number (A000217).

Terms

    a(0) =0a(1) =1a(2) =4a(3) =24a(4) =309a(5) =8807a(6) =530356a(7) =65679652a(8) =16512273616

External references