Expansion of 1 - 1/Sum_{k>=0} k!!*x^k.

Terms

a(0) =0a(1) =1a(2) =1a(3) =0a(4) =3a(5) =1a(6) =18a(7) =13a(8) =155a(9) =168a(10) =1691a(11) =2381a(12) =22022a(13) =37401a(14) =331087a(15) =649036a(16) =5626103a(17) =12372161a(18) =106486594a(19) =257573405a(20) =2220690451a(21) =5824952232a(22) =50593271507a(23) =142387607469