a(n) = Sum_{k=0..n} binomial(n,k) * binomial(n+3*k-1,n-k).
A389322
a(n) = Sum_{k=0..n} binomial(n,k) * binomial(n+3*k-1,n-k).
Terms
- a(0) =1a(1) =1a(2) =9a(3) =55a(4) =345a(5) =2236a(6) =14727a(7) =98134a(8) =659801a(9) =4467160a(10) =30413924a(11) =208016337a(12) =1428159207a(13) =9836845630a(14) =67941521286a(15) =470386502500
External references
- oeis: A389322