G.f.: A(x) = exp( Sum_{n>=1} sigma(n) * C(2*n-1,n) * x^n/n ), a power series in x with integer coefficients.
A156305
G.f.: A(x) = exp( Sum_{n>=1} sigma(n) * C(2*n-1,n) * x^n/n ), a power series in x with integer coefficients.
Terms
- a(0) =1a(1) =1a(2) =5a(3) =18a(4) =87a(5) =290a(6) =1553a(7) =5015a(8) =25436a(9) =94500a(10) =431464a(11) =1519749a(12) =8024004a(13) =26746757a(14) =125190249a(15) =498138920a(16) =2221127601a(17) =8020960187a(18) =38836436844a(19) =138444409552a(20) =655009491676
External references
- oeis: A156305