a(n) = (n!^2*n^(n-1)/4) * Sum_{k=4..n} A000276(k) / (n^k * (n-k)!).
A377246
a(n) = (n!^2*n^(n-1)/4) * Sum_{k=4..n} A000276(k) / (n^k * (n-k)!).
Terms
- a(0) =0a(1) =0a(2) =0a(3) =108a(4) =25200a(5) =6566400a(6) =2263917600
External references
- oeis: A377246