Let T(n) be the n-th triangular number n*(n+1)/2; then a(n) = n-th iteration T(T(T(...(n)))).

A099129

Let T(n) be the n-th triangular number n*(n+1)/2; then a(n) = n-th iteration T(T(T(...(n)))).

Terms

    a(0) =0a(1) =1a(2) =6a(3) =231a(4) =1186570

External references