G.f.: Sum_{n>=0} x^n / (1-3*x)^(2*n+1) * [Sum_{k=0..n} C(n,k)^2 * x^k] * [Sum_{k=0..n} C(n,k)^2 * 3^k * x^k].
A246813
G.f.: Sum_{n>=0} x^n / (1-3*x)^(2*n+1) * [Sum_{k=0..n} C(n,k)^2 * x^k] * [Sum_{k=0..n} C(n,k)^2 * 3^k * x^k].
Terms
- a(0) =1a(1) =4a(2) =23a(3) =152a(4) =1085a(5) =8156a(6) =63579a(7) =509136a(8) =4161649a(9) =34566580a(10) =290798551a(11) =2471871784a(12) =21191824645a(13) =182984610220
External references
- oeis: A246813