Series inversion of A007296.

Terms

a(0) =1a(1) =2a(2) =-1a(3) =3a(4) =-11a(5) =44a(6) =-187a(7) =827a(8) =-3751a(9) =17313a(10) =-81004a(11) =383390a(12) =-1833029a(13) =8843224a(14) =-43007753a(15) =210670655a(16) =-1038597645a(17) =5149654796a(18) =-25664518105a(19) =128493771585a(20) =-645988558986