Negative numbers in base -2.

Terms

a(0) =11a(1) =10a(2) =1101a(3) =1100a(4) =1111a(5) =1110a(6) =1001a(7) =1000a(8) =1011a(9) =1010a(10) =110101a(11) =110100a(12) =110111a(13) =110110a(14) =110001a(15) =110000a(16) =110011a(17) =110010a(18) =111101a(19) =111100a(20) =111111a(21) =111110a(22) =111001a(23) =111000a(24) =111011a(25) =111010a(26) =100101a(27) =100100a(28) =100111a(29) =100110