O.g.f.: Sum_{n>=0} n! * x^n * Product_{k=1..n} (k + x) / (1 + k^2*x + k*x^2).
A221370
O.g.f.: Sum_{n>=0} n! * x^n * Product_{k=1..n} (k + x) / (1 + k^2*x + k*x^2).
Terms
- a(0) =1a(1) =1a(2) =4a(3) =21a(4) =183a(5) =2362a(6) =42449a(7) =1012897a(8) =30961412a(9) =1179154241a(10) =54727128731
External references
- oeis: A221370