a(n) = (3^n-1)*(3^n-3)*(3^n+3)/4!.

A275635

a(n) = (3^n-1)*(3^n-3)*(3^n+3)/4!.

Terms

    a(0) =0a(1) =0a(2) =24a(3) =780a(4) =21840a(5) =595320a(6) =16120104a(7) =435647940a(8) =11766101280a(9) =317717078640

External references