a(n) = Sum_{k=0..n} 3^(n-k) * binomial(n+2,k+2) * binomial(2*k+4,k+4).

A387275

a(n) = Sum_{k=0..n} 3^(n-k) * binomial(n+2,k+2) * binomial(2*k+4,k+4).

Terms

    a(0) =1a(1) =15a(2) =154a(3) =1350a(4) =10890a(5) =83650a(6) =623056a(7) =4547520a(8) =32735085a(9) =233369675a(10) =1652203542a(11) =11638252730a(12) =81674873553a(13) =571575363975

External references