676196049060domain: NAppears in sequencesa(n) = 3*binomial(4*n-1, n-1)/(4*n-1).at n=14A006632G.f. A(x) satisfies: A(x*(1+x)^3) = 1 + x.at n=15A171790Expansion of g.f. A(x) satisfying A(x) = 1 + x*(3*A(x)^2 + A(-x)^2)/4.at n=29A369082