Expansion of Sum_{k>=0} x^(2*k)/Product_{j=1..k} (1 - j*2*x).

Terms

a(0) =1a(1) =0a(2) =1a(3) =2a(4) =5a(5) =14a(6) =45a(7) =164a(8) =661a(9) =2884a(10) =13461a(11) =66894a(12) =353217a(13) =1977146a(14) =11691481a(15) =72734088a(16) =474172777a(17) =3229062120a(18) =22914397417a(19) =169128976922