a(n) = [x^(3*n)] Product_{k=0..n} 1/(1 - k*x)^2.

A384206

a(n) = [x^(3*n)] Product_{k=0..n} 1/(1 - k*x)^2.

Terms

    a(0) =1a(1) =4a(2) =1291a(3) =2107596a(4) =9822847079

External references