a(n) is the constant term in the expansion of Product_{k=1..n} (x^k + 1 + 1/x^k)^n.

A350305

a(n) is the constant term in the expansion of Product_{k=1..n} (x^k + 1 + 1/x^k)^n.

Terms

    a(0) =1a(1) =1a(2) =13a(3) =1437a(4) =1884211a(5) =24657701475

External references