G.f. A(x) satisfies: A(x) = x^2 + x^3 * A(x/(1 + x)) / (1 + x).

Terms

a(0) =0a(1) =0a(2) =1a(3) =0a(4) =0a(5) =1a(6) =-3a(7) =6a(8) =-9a(9) =6a(10) =27a(11) =-169a(12) =645a(13) =-1995a(14) =5122a(15) =-9570a(16) =1242a(17) =109739a(18) =-756648a(19) =3733128a(20) =-15527337a(21) =55626585a(22) =-161247102a(23) =260402511a(24) =1028417064a(25) =-14243992155a(26) =102551438561a(27) =-595149283191