G.f. A(x) satisfies 1 = Sum_{n>=0} (-x)^(n^2) * A(x)^(n+1).

Terms

a(0) =1a(1) =1a(2) =2a(3) =5a(4) =13a(5) =37a(6) =111a(7) =345a(8) =1103a(9) =3604a(10) =11977a(11) =40356a(12) =137543a(13) =473317a(14) =1642258a(15) =5738828a(16) =20179338a(17) =71346433a(18) =253485527a(19) =904536366a(20) =3240418665a(21) =11649734335a(22) =42017535527a(23) =151992797355a(24) =551298507620