G.f. A(x) satisfies: A(x) = x + x^3 * A(x/(1 + x)) / (1 + x).

Terms

a(0) =0a(1) =1a(2) =0a(3) =0a(4) =1a(5) =-2a(6) =3a(7) =-3a(8) =-2a(9) =24a(10) =-94a(11) =280a(12) =-687a(13) =1270a(14) =-655a(15) =-9306a(16) =65087a(17) =-306724a(18) =1202250a(19) =-4033365a(20) =10855578a(21) =-15470865a(22) =-69819687a(23) =850568716a(24) =-5679272040a(25) =30749200898a(26) =-144912453016a(27) =593521998765