Binomial coefficient C(3n,n-11).

Terms

a(0) =1a(1) =36a(2) =741a(3) =11480a(4) =148995a(5) =1712304a(6) =18009460a(7) =177100560a(8) =1652411475a(9) =14783142660a(10) =127805525001