a(n) = Sum_{k=0..n} binomial(3*n+1,k) * binomial(3*n-k-1,n-k).

A386833

a(n) = Sum_{k=0..n} binomial(3*n+1,k) * binomial(3*n-k-1,n-k).

Terms

    a(0) =1a(1) =6a(2) =59a(3) =656a(4) =7701a(5) =93210a(6) =1150495a(7) =14395428a(8) =181936169a(9) =2317140014a(10) =29691138099a(11) =382334271544

External references