A007089 - OEIS

A007089 as a simple table

n	a(n)
0	0
1	1
2	2
3	10
4	11
5	12
6	20
7	21
8	22
9	100
10	101
11	102
12	110
13	111
14	112
15	120
16	121
17	122
18	200
19	201
20	202
21	210
22	211
23	212
24	220
25	221
26	222
27	1000
28	1001
29	1002
30	1010
31	1011
32	1012
33	1020
34	1021
35	1022
36	1100
37	1101
38	1102
39	1110
40	1111
41	1112
42	1120
43	1121
44	1122
45	1200
46	1201
47	1202
48	1210
49	1211

[0,1,2,10,11,12,20,21,22,100,101,102,110,111,112, 120,121,122,200,201,202,210,211,212,220,221,222, 1000,1001,1002,1010,1011,1012,1020,1021,1022,1100, 1101,1102,1110,1111,1112,1120,1121,1122,1200,1201, 1202,1210,1211]