G.f. A(x) satisfies A(x) = (1 + x*A(x)^2) * (1 + x^3*A(x)^7).

Terms

a(0) =1a(1) =1a(2) =2a(3) =6a(4) =24a(5) =108a(6) =503a(7) =2385a(8) =11537a(9) =56992a(10) =286769a(11) =1464317a(12) =7564803a(13) =39457205a(14) =207500615a(15) =1099066181a(16) =5858206629a(17) =31399478619a(18) =169132215962a(19) =915057263082