A001202 a(1)=0, a(2n)=a(n)+1, a(2n+1)=10*a(n+1).

0, 1, 10, 2, 100, 11, 20, 3, 1000, 101, 110, 12, 200, 21, 30, 4, 10000, 1001, 1010, 102, 1100, 111, 120, 13, 2000, 201, 210, 22, 300, 31, 40, 5, 100000, 10001, 10010, 1002, 10100, 1011, 1020, 103, 11000, 1101