a(n) = Sum_{k=0..n} binomial(n,k) * binomial(n+k,k) * n^k.
A331656
a(n) = Sum_{k=0..n} binomial(n,k) * binomial(n+k,k) * n^k.
Terms
- a(0) =1a(1) =3a(2) =37a(3) =847a(4) =28401a(5) =1256651a(6) =69125869a(7) =4548342975a(8) =348434664769
External references
- oeis: A331656