a(n) is the constant term in expansion of Product_{k=1..n} (x^k + 1 + 1/x^k)^3.

A369372

a(n) is the constant term in expansion of Product_{k=1..n} (x^k + 1 + 1/x^k)^3.

Terms

    a(0) =1a(1) =7a(2) =85a(3) =1437a(4) =26707a(5) =534513a(6) =11255951a(7) =245612031a(8) =5503639327a(9) =125900330437

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