G.f.: Sum_{n>=0} x^n / (1-3*x)^(2*n+1) * [Sum_{k=0..n} C(n,k)^2 * 2^k * x^k] * [Sum_{k=0..n} C(n,k)^2 * 3^k * x^k].
A246423
G.f.: Sum_{n>=0} x^n / (1-3*x)^(2*n+1) * [Sum_{k=0..n} C(n,k)^2 * 2^k * x^k] * [Sum_{k=0..n} C(n,k)^2 * 3^k * x^k].
Terms
- a(0) =1a(1) =4a(2) =24a(3) =168a(4) =1286a(5) =10440a(6) =88112a(7) =764368a(8) =6766278a(9) =60828024a(10) =553529808a(11) =5086837680a(12) =47127896444a(13) =439608960656
External references
- oeis: A246423