Sums of two powers of 10.

Terms

a(0) =2a(1) =11a(2) =20a(3) =101a(4) =110a(5) =200a(6) =1001a(7) =1010a(8) =1100a(9) =2000a(10) =10001a(11) =10010a(12) =10100a(13) =11000a(14) =20000a(15) =100001a(16) =100010a(17) =100100a(18) =101000a(19) =110000a(20) =200000a(21) =1000001a(22) =1000010a(23) =1000100a(24) =1001000a(25) =1010000a(26) =1100000a(27) =2000000a(28) =10000001a(29) =10000010