a(n) = Sum_{k=0..n} (n!/k!)^2*binomial(n-1,k-1).
A119399
a(n) = Sum_{k=0..n} (n!/k!)^2*binomial(n-1,k-1).
Terms
- a(0) =1a(1) =1a(2) =5a(3) =55a(4) =1057a(5) =31301a(6) =1319581a(7) =74996755a(8) =5521809665a(9) =510921831817
External references
- oeis: A119399