Binomial coefficient C(3n,n-10).

Terms

a(0) =1a(1) =33a(2) =630a(3) =9139a(4) =111930a(5) =1221759a(6) =12271512a(7) =115775100a(8) =1040465790a(9) =8996462475a(10) =75394027566a(11) =615790256823