G.f.: Sum_{n>=0} d^n/dx^n (2*x + x^2)^(2*n) / n!.
A215129
G.f.: Sum_{n>=0} d^n/dx^n (2*x + x^2)^(2*n) / n!.
Terms
- a(0) =1a(1) =8a(2) =108a(3) =1604a(4) =25000a(5) =400680a(6) =6539932a(7) =108124704a(8) =1804745052a(9) =30345973020a(10) =513246523504
External references
- oeis: A215129