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

Terms

a(0) =1a(1) =2a(2) =6a(3) =12a(4) =30a(5) =66a(6) =156a(7) =354a(8) =822a(9) =1884a(10) =4350a(11) =10002a(12) =23052a(13) =53058a(14) =122214a(15) =281388a(16) =648030a(17) =1492194a(18) =3436284a(19) =7912866a(20) =18221718a(21) =41960316a(22) =96625470a(23) =222506418a(24) =512382828a(25) =1179902082a(26) =2717050566a(27) =6256756812a(28) =14407908510a(29) =33178178946