G.f.: Sum_{n>=0} x^n / (1-x)^(4*n+1) * [Sum_{k=0..2*n} C(2*n,k)^2 * x^k]^2.
A246570
G.f.: Sum_{n>=0} x^n / (1-x)^(4*n+1) * [Sum_{k=0..2*n} C(2*n,k)^2 * x^k]^2.
Terms
- a(0) =1a(1) =2a(2) =15a(3) =116a(4) =1001a(5) =9322a(6) =89363a(7) =881376a(8) =8860677a(9) =90407666a(10) =933482527a(11) =9731366060a(12) =102259648701
External references
- oeis: A246570