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

Terms

a(0) =1a(1) =2a(2) =4a(3) =11a(4) =28a(5) =68a(6) =169a(7) =422a(8) =1048a(9) =2603a(10) =6472a(11) =16088a(12) =39985a(13) =99386a(14) =247036a(15) =614027a(16) =1526212a(17) =3793532a(18) =9429145a(19) =23436926a(20) =58254448a(21) =144796331a(22) =359903440a(23) =894570224a(24) =2223529441a(25) =5526769202a(26) =13737249076a(27) =34145086475a(28) =84870480556