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

Terms

a(0) =0a(1) =2a(2) =2a(3) =6a(4) =12a(5) =28a(6) =62a(7) =140a(8) =314a(9) =706a(10) =1586a(11) =3564a(12) =8008a(13) =17994a(14) =40432a(15) =90850a(16) =204138a(17) =458694a(18) =1030676a(19) =2315908a(20) =5203798a(21) =11692828a(22) =26273546a(23) =59036122a(24) =132652962a(25) =298068500a(26) =669753840a(27) =1504923218a(28) =3381531776a(29) =7598232930