a(n) = binomial(4*n,2*n)*binomial(3*n,2*n).

A275653

a(n) = binomial(4*n,2*n)*binomial(3*n,2*n).

Terms

    a(0) =1a(1) =18a(2) =1050a(3) =77616a(4) =6370650a(5) =554822268a(6) =50199951984

External references