Expansion of 1/(1 - x/(1 - x)^3)^3.

Terms

a(0) =1a(1) =3a(2) =15a(3) =64a(4) =261a(5) =1032a(6) =3982a(7) =15066a(8) =56094a(9) =206068a(10) =748452a(11) =2691966a(12) =9600233a(13) =33982197a(14) =119495229a(15) =417724302a(16) =1452550371a(17) =5026878774a(18) =17321417650a(19) =59450099958a(20) =203306331429a(21) =692955932103