A038528 - OEIS

A038528 as a simple table

n	a(n)
1	1
2	12
3	20
4	21
5	22
6	123
7	132
8	133
9	203
10	213
11	223
12	230
13	231
14	232
15	300
16	301
17	303
18	312
19	313
20	320
21	321
22	322
23	330
24	331
25	333
26	1234
27	1243
28	1244
29	1324
30	1334
31	1342
32	1343
33	1423
34	1424
35	1432
36	1433
37	1442
38	1444
39	2034
40	2043
41	2044
42	2134
43	2143
44	2144
45	2234

[1,12,20,21,22,123,132,133,203,213,223,230,231, 232,300,301,303,312,313,320,321,322,330,331,333, 1234,1243,1244,1324,1334,1342,1343,1423,1424,1432, 1433,1442,1444,2034,2043,2044,2134,2143,2144,2234]