Symmetrical product form polynomial as triangle sequence coefficients: q(x,n)=Product[x + 2*n - i + 1, {i, 0, n - 1}]; p(x,n)=q(x,n)+x^2+x^n*q(1/x,m);t(n,m)=coefficients(p(x,n).

A155725

Symmetrical product form polynomial as triangle sequence coefficients: q(x,n)=Product[x + 2*n - i + 1, {i, 0, n - 1}]; p(x,n)=q(x,n)+x^2+x^n*q(1/x,m);t(n,m)=coefficients(p(x,n).