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

A386869

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

Terms

    a(0) =1a(1) =11a(2) =168a(3) =2839a(4) =50333a(5) =917604a(6) =17036260a(7) =320383295a(8) =6082829067a(9) =116342007859

External references