Coefficient triangle sequence of a polynomial recursion: p(x,n)=(x + 1)*(p(x, n - 1) + 3^(n - 3)*Sum[x^i, {i, 1, n - 2}]); Row sums approximate 2*3^n.

A153312

Coefficient triangle sequence of a polynomial recursion: p(x,n)=(x + 1)*(p(x, n - 1) + 3^(n - 3)*Sum[x^i, {i, 1, n - 2}]); Row sums approximate 2*3^n.