G.f.: 1/(1-x) = Sum_{n>=0} a(n) * x^n / Product_{k=1..2*n} (1 + k*x).

A208831

G.f.: 1/(1-x) = Sum_{n>=0} a(n) * x^n / Product_{k=1..2*n} (1 + k*x).

Terms

    a(0) =1a(1) =1a(2) =4a(3) =34a(4) =470a(5) =9246a(6) =239254a(7) =7735818a(8) =301515326a(9) =13798284326a(10) =726653380406

External references