Revert transform of (1 + 2x - x^2)/(1 + 3x + 2x^2 + x^3).

Terms

a(0) =1a(1) =1a(2) =2a(3) =4a(4) =10a(5) =24a(6) =65a(7) =171a(8) =482a(9) =1338a(10) =3868a(11) =11110a(12) =32707a(13) =96137a(14) =287001a(15) =857577a(16) =2588794a(17) =7830730a(18) =23854028a(19) =72840384a(20) =223557060a(21) =687811608a(22) =2124300494a(23) =6576110024a(24) =20418808851a(25) =63534855143a(26) =198178318008a(27) =619338524116