E.g.f.: Sum_{n>=1} log((1 + exp(2*x^n))/2).

Terms

a(0) =1a(1) =3a(2) =6a(3) =34a(4) =120a(5) =1096a(6) =5040a(7) =56848a(8) =362880a(9) =5451136a(10) =39916800a(11) =688876288a(12) =6227020800a(13) =130789805056