Expansion of e.g.f. exp(x^2/2 * (1 + x)).

Terms

a(0) =1a(1) =0a(2) =1a(3) =3a(4) =3a(5) =30a(6) =105a(7) =315a(8) =2625a(9) =11340a(10) =57645a(11) =467775a(12) =2505195a(13) =17027010a(14) =142026885a(15) =922296375a(16) =7493911425a(17) =65886420600a(18) =503693415225