a(n) = 1/2 * (-1 + Sum_{k=0..n} binomial(2*n,2*k)*(n+1)^(n-k)*n^k).
A322746
a(n) = 1/2 * (-1 + Sum_{k=0..n} binomial(2*n,2*k)*(n+1)^(n-k)*n^k).
Terms
- a(0) =0a(1) =1a(2) =24a(3) =675a(4) =25920a(5) =1275125a(6) =76545000a(7) =5425069447a(8) =443365544448
External references
- oeis: A322746