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

Terms

a(0) =1a(1) =2a(2) =4a(3) =10a(4) =28a(5) =82a(6) =244a(7) =730a(8) =2188a(9) =6562a(10) =19684a(11) =59050a(12) =177148a(13) =531442a(14) =1594324a(15) =4782970a(16) =14348908a(17) =43046722a(18) =129140164a(19) =387420490a(20) =1162261468a(21) =3486784402a(22) =10460353204a(23) =31381059610a(24) =94143178828a(25) =282429536482a(26) =847288609444