a(n) = (5*n)!*(9*n/2)!*(n/2)! / ((2*n)!^2 * (5*n/2)!^2 * n!).

A365026

a(n) = (5*n)!*(9*n/2)!*(n/2)! / ((2*n)!^2 * (5*n/2)!^2 * n!).

Terms

    a(0) =1a(1) =126a(2) =79380a(3) =65523780a(4) =60634147860

External references