Expansion of -(sqrt(x^4-4*x^3-6*x^2-4*x+1) +x^2-2*x-1)/4.

Terms

a(0) =0a(1) =1a(2) =1a(3) =3a(4) =9a(5) =33a(6) =129a(7) =531a(8) =2265a(9) =9921a(10) =44361a(11) =201651a(12) =929073a(13) =4328865a(14) =20362137a(15) =96562659a(16) =461169873a(17) =2216134401a(18) =10707788721a(19) =51988771107a(20) =253515373305