Expansion of (1-3*x+x^2)^2/(1-9*x+28*x^2-35*x^3+15*x^4-x^5).

Terms

a(0) =1a(1) =3a(2) =10a(3) =35a(4) =126a(5) =460a(6) =1690a(7) =6225a(8) =22950a(9) =84626a(10) =312019a(11) =1150208a(12) =4239225a(13) =15621426a(14) =57556155a(15) =212037241a(16) =781074572a(17) =2877011660a(18) =10596599460a(19) =39027676220a(20) =143735627861a(21) =529352597361