G.f. A(x) satisfies: x = Sum_{n=-oo..+oo} (-x)^n * (1 + A(x)*x^n)^n.

Terms

a(0) =1a(1) =1a(2) =3a(3) =8a(4) =26a(5) =69a(6) =186a(7) =554a(8) =1606a(9) =4772a(10) =14825a(11) =45920a(12) =143586a(13) =455561a(14) =1446777a(15) =4622609a(16) =14885492a(17) =48099814a(18) =156175165a(19) =509527438a(20) =1667502213a(21) =5475430124a(22) =18036181574a(23) =59562083008a(24) =197197284543a(25) =654439115129