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

Terms

a(0) =1a(1) =-2a(2) =3a(3) =-6a(4) =12a(5) =-24a(6) =48a(7) =-96a(8) =192a(9) =-384a(10) =768a(11) =-1536a(12) =3072a(13) =-6144a(14) =12288a(15) =-24576a(16) =49152a(17) =-98304a(18) =196608a(19) =-393216a(20) =786432a(21) =-1572864a(22) =3145728a(23) =-6291456a(24) =12582912a(25) =-25165824a(26) =50331648a(27) =-100663296a(28) =201326592a(29) =-402653184