a(n) is the constant term in expansion of Product_{k=1..n} (x^k + 1 + 1/x^k)^4.

A369373

a(n) is the constant term in expansion of Product_{k=1..n} (x^k + 1 + 1/x^k)^4.

Terms

    a(0) =1a(1) =19a(2) =701a(3) =33873a(4) =1884211a(5) =113091013a(6) =7138569079a(7) =466998324373

External references