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

Terms

a(0) =0a(1) =0a(2) =1a(3) =4a(4) =14a(5) =42a(6) =119a(7) =322a(8) =847a(9) =2180a(10) =5521a(11) =13804a(12) =34160a(13) =83818a(14) =204204a(15) =494494a(16) =1191227a(17) =2856666a(18) =6823334a(19) =16240714a(20) =38534657a(21) =91175154a(22) =215179125a(23) =506670394a(24) =1190534467a(25) =2792076392a(26) =6536567296a(27) =15278103876a(28) =35656587624a(29) =83101366684