E.g.f.: 2 - exp(2) + Sum_{n>=1} 2^n * exp(3*x^n) / n!.

Terms

a(0) =1a(1) =6a(2) =30a(3) =78a(4) =426a(5) =582a(6) =12450a(7) =4758a(8) =407010a(9) =2218182a(10) =19172370a(11) =360438a(12) =4755166050a(13) =3213222a(14) =85631151090a(17) =258673542a(19) =2326095798a(23) =188311523478