Coefficient of x^n in the expansion of ( (1-x) / (1-x-x^2) )^n.

Terms

a(0) =1a(1) =0a(2) =2a(3) =3a(4) =14a(5) =35a(6) =125a(7) =371a(8) =1238a(9) =3909a(10) =12847a(11) =41580a(12) =136577a(13) =447187a(14) =1473341a(15) =4855703a(16) =16053830a(17) =53138243a(18) =176233967a(19) =585202261a(20) =1945964079a(21) =6478043120a(22) =21588979876a(23) =72016891508a(24) =240452892569a(25) =803489258285