a(n) = binomial(12*n-1,3*n-1)/((6*n-1)*(12*n-1)).

A055579

a(n) = binomial(12*n-1,3*n-1)/((6*n-1)*(12*n-1)).

Terms

    a(0) =1a(1) =133a(2) =39556a(3) =16112057a(4) =7772368380

External references