G.f.: Sum_{n>=0} n^n * x^n * (2 + n*x)^n / (1 + n*x)^(2*n+2).
A240956
G.f.: Sum_{n>=0} n^n * x^n * (2 + n*x)^n / (1 + n*x)^(2*n+2).
Terms
- a(0) =1a(1) =2a(2) =9a(3) =72a(4) =830a(5) =12420a(6) =228060a(7) =4959360a(8) =124589304a(9) =3550050000a(10) =113116311000
External references
- oeis: A240956