G.f.: exp( Sum_{n>=1} x^n/n * Sum_{k=0..n} binomial(n*k, k^2) ).
A228809
G.f.: exp( Sum_{n>=1} x^n/n * Sum_{k=0..n} binomial(n*k, k^2) ).
Terms
- a(0) =1a(1) =2a(2) =4a(3) =12a(4) =94a(5) =2195a(6) =158904a(7) =31681195a(8) =13904396167
External references
- oeis: A228809