Expansion of g.f. 1/(1-3*x-x^2/(1-3*x-x^2/(1-3*x))).

Terms

a(0) =1a(1) =3a(2) =10a(3) =36a(4) =137a(5) =543a(6) =2218a(7) =9264a(8) =39329a(9) =168939a(10) =731770a(11) =3188364a(12) =13948745a(13) =61196775a(14) =269007994a(15) =1184076216a(16) =5216618369a(17) =22996827795a(18) =101421591466a(19) =447422614068