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

Terms

a(0) =1a(1) =3a(2) =12a(3) =48a(4) =189a(5) =747a(6) =2952a(7) =11664a(8) =46089a(9) =182115a(10) =719604a(11) =2843424a(12) =11235429a(13) =44395371a(14) =175422672a(15) =693160416a(16) =2738935377a(17) =10822555395a(18) =42763953564a(19) =168976333008a(20) =667688525901