a(n) = binomial(n^2+n+1,n) * (n+1) / (n^2+n+1) for n>=0.
A228509
a(n) = binomial(n^2+n+1,n) * (n+1) / (n^2+n+1) for n>=0.
Terms
- a(0) =1a(1) =2a(2) =9a(3) =88a(4) =1425a(5) =32886a(6) =992446a(7) =37106784a(8) =1657248417a(9) =86128357150
External references
- oeis: A228509