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

Terms

a(0) =0a(1) =0a(2) =0a(3) =0a(4) =1a(5) =2a(6) =3a(7) =6a(8) =13a(9) =26a(10) =52a(11) =108a(12) =226a(13) =472a(14) =993a(15) =2106a(16) =4485a(17) =9586a(18) =20576a(19) =44332a(20) =95814a(21) =207688a(22) =451438a(23) =983736a(24) =2148618a(25) =4702976a(26) =10314672a(27) =22664452a(28) =49887084a(29) =109985772