E.g.f.: Product_{n>=1} (cos(x^n/n) + sin(x^n/n)).

Terms

a(0) =1a(1) =1a(2) =0a(3) =4a(4) =6a(5) =30a(6) =348a(7) =1580a(8) =12516a(9) =114884a(10) =1375776a(11) =12239280a(12) =160067160a(13) =1966619512a(14) =28104385008a(15) =428735710000