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

Terms

a(0) =1a(1) =1a(2) =1a(3) =3a(4) =5a(5) =18a(6) =35a(7) =136a(8) =285a(9) =1155a(10) =2530a(11) =10530a(12) =23751a(13) =100688a(14) =231880a(15) =996336a(16) =2330445a(17) =10116873a(18) =23950355a(19) =104819165a(20) =250543370a(21) =1103722620a(22) =2658968130a(23) =11777187240a(24) =28558343775a(25) =127067830773a(26) =309831575760