a(n) = (1/n!) * (7*n)!/(7*n/2)! * (5*n/2)!/(5*n)!.

A262733

a(n) = (1/n!) * (7*n)!/(7*n/2)! * (5*n/2)!/(5*n)!.

Terms

    a(0) =1a(1) =12a(2) =286a(3) =7680a(4) =217350a(5) =6336512a(6) =188296108a(7) =5670567936a(8) =172459427910

External references