G.f.: Sum_{n>=0} n^n * x^n * (1 + 2*n*x)^n / (1 + n*x + 2*n^2*x^2)^(n+1).
A240958
G.f.: Sum_{n>=0} n^n * x^n * (1 + 2*n*x)^n / (1 + n*x + 2*n^2*x^2)^(n+1).
Terms
- a(0) =1a(1) =1a(2) =4a(3) =30a(4) =296a(5) =3840a(6) =60480a(7) =1127280a(8) =24240384a(9) =590728320a(10) =16090099200a(11) =484387706880
External references
- oeis: A240958