a(n) = Sum_{k=0..n} 3^(n-k) * binomial(n+3,k+3) * binomial(2*k+6,k+6).
A387276
a(n) = Sum_{k=0..n} 3^(n-k) * binomial(n+3,k+3) * binomial(2*k+6,k+6).
Terms
- a(0) =1a(1) =20a(2) =255a(3) =2650a(4) =24521a(5) =210840a(6) =1725234a(7) =13631700a(8) =104993955a(9) =793367300a(10) =5907885412a(11) =43495473840a(12) =317355930255
External references
- oeis: A387276