a(n) = (3*n+1)!/(3^n*n!) * Product_{k=1..n} (3*k - 2), for n >= 0.

A357543

a(n) = (3*n+1)!/(3^n*n!) * Product_{k=1..n} (3*k - 2), for n >= 0.

Terms

    a(0) =1a(1) =8a(2) =1120a(3) =627200a(4) =896896000

External references