A167503 - OEIS

A167503 as a simple table

n	a(n)
1	1
2	2
3	10
4	12
5	20
6	21
7	100
8	101
9	102
10	112
11	121
12	122
13	201
14	202
15	210
16	211
17	212
18	220
19	221
20	222
21	1000
22	1001
23	1002
24	1011
25	1012
26	1021
27	1022
28	1100
29	1102
30	1110
31	1111
32	1112
33	1120
34	1121
35	1122
36	1200
37	1202
38	1210
39	1211
40	1212
41	1220
42	1221
43	1222
44	2010
45	2020
46	2021
47	2101

[1,2,10,12,20,21,100,101,102,112,121,122,201,202, 210,211,212,220,221,222,1000,1001,1002,1011,1012, 1021,1022,1100,1102,1110,1111,1112,1120,1121,1122, 1200,1202,1210,1211,1212,1220,1221,1222,2010,2020, 2021,2101]