a(2*n) = 10*a(n), a(2*n+1) = a(n) + a(n+1).

Terms

a(0) =1a(1) =10a(2) =11a(3) =100a(4) =21a(5) =110a(6) =111a(7) =1000a(8) =121a(9) =210a(10) =131a(11) =1100a(12) =221a(13) =1110a(14) =1111a(15) =10000a(16) =1121a(17) =1210a(18) =331a(19) =2100a(20) =341a(21) =1310a(22) =1231a(23) =11000a(24) =1321a(25) =2210a(26) =1331a(27) =11100a(28) =2221a(29) =11110