G.f.: Sum_{n>=0} x^n * Product_{k=1..n} (k + x) / (1 - k*x - x^2).
A231274
G.f.: Sum_{n>=0} x^n * Product_{k=1..n} (k + x) / (1 - k*x - x^2).
Terms
- a(0) =1a(1) =1a(2) =4a(3) =18a(4) =104a(5) =736a(6) =6232a(7) =61632a(8) =698144a(9) =8917120a(10) =126807520a(11) =1987075872a(12) =34018221728a(13) =631698903712
External references
- oeis: A231274