G.f. A(x) satisfies: [x^(2n)] A(x)/Catalan(x)^n = A001764(n) = C(3n,n)/(2n+1) and [x^(2n+1)] A(x)/Catalan(x)^n = A001764(n+1) for n>=0, where Catalan(x) is the g.f. of A000108.

A127927

G.f. A(x) satisfies: [x^(2n)] A(x)/Catalan(x)^n = A001764(n) = C(3n,n)/(2n+1) and [x^(2n+1)] A(x)/Catalan(x)^n = A001764(n+1) for n>=0, where Catalan(x) is the g.f. of A000108.

Terms

    a(0) =1a(1) =1a(2) =3a(3) =9a(4) =31a(5) =108a(6) =391a(7) =1431a(8) =5319a(9) =19926a(10) =75252a(11) =285750a(12) =1090491a(13) =4177774a(14) =16060401a(15) =61916977a(16) =239307063a(17) =926929746a(18) =3597296770a(19) =13984508500a(20) =54448030092a(21) =212282062488a(22) =828673761978

External references