G.f.: exp( Sum_{n>=1} x^n/n * Sum_{k=0..n} binomial(n*k, k^2) * x^k ).
A228905
G.f.: exp( Sum_{n>=1} x^n/n * Sum_{k=0..n} binomial(n*k, k^2) * x^k ).
Terms
- a(0) =1a(1) =1a(2) =2a(3) =3a(4) =5a(5) =12a(6) =33a(7) =139a(8) =1251a(9) =10598a(10) =176642a(11) =4720781a(12) =106779821a(13) =5953841083a(14) =373265833332
External references
- oeis: A228905