G.f.: Sum_{n>=0} x^n / (1-2*x)^(2*n+1) * [Sum_{k=0..n} C(n,k)^2 * 2^k * x^k] * [Sum_{k=0..n} C(n,k)^2 * 4^k * x^k].
A249921
G.f.: Sum_{n>=0} x^n / (1-2*x)^(2*n+1) * [Sum_{k=0..n} C(n,k)^2 * 2^k * x^k] * [Sum_{k=0..n} C(n,k)^2 * 4^k * x^k].
Terms
- a(0) =1a(1) =3a(2) =17a(3) =111a(4) =805a(5) =6147a(6) =48641a(7) =394863a(8) =3266629a(9) =27421395a(10) =232867889a(11) =1996302447a(12) =17248208485a(13) =150013649955
External references
- oeis: A249921