A089564 - cp's OEIS frontend

A089564 a(1) = 9. For n > 1, a(n) is the least unused number such that the decimal concatenation a(n)a(n-1)...a(2)a(1) is prime.

n	a(n)
1	9
2	1
3	4
4	5
5	3
6	7
7	12
8	11
9	13
10	42
11	26
12	10
13	17
14	16
15	20
16	82
17	29
18	78
19	57
20	27
21	28
22	66
23	45
24	6
25	69
26	33
27	236
28	40
29	116
30	237
31	196
32	65
33	133
34	90
35	60
36	72
37	80
38	61
39	126
40	24
41	153
42	68
43	88
44	122
45	43
46	156
47	231
48	285
49	125
50	177
51	249
52	106
53	36
54	147
55	23
56	208
57	483
58	138
59	281
60	63
61	108
62	22
63	38
64	75
65	159

[9, 1, 4, 5, 3, 7, 12, 11, 13, 42, 26, 10, 17, 16, 20, 82, 29, 78, 57, 27, 28, 66, 45, 6, 69, 33, 236, 40, 116, 237, 196, 65, 133, 90, 60, 72, 80, 61, 126, 24, 153, 68, 88, 122, 43, 156, 231, 285, 125, 177, 249, 106, 36, 147, 23, 208, 483, 138, 281, 63, 108, 22, 38, 75, 159]

cp's OEIS Frontend

A089564 a(1) = 9. For n > 1, a(n) is the least unused number such that the decimal concatenation a(n)a(n-1)...a(2)a(1) is prime.

Table of values

List of values

n	a(n)
1	9
2	1
3	4
4	5
5	3
6	7
7	12
8	11
9	13
10	42
11	26
12	10
13	17
14	16
15	20
16	82
17	29
18	78
19	57
20	27
21	28
22	66
23	45
24	6
25	69
26	33
27	236
28	40
29	116
30	237
31	196
32	65
33	133
34	90
35	60
36	72
37	80
38	61
39	126
40	24
41	153
42	68
43	88
44	122
45	43
46	156
47	231
48	285
49	125
50	177
51	249
52	106
53	36
54	147
55	23
56	208
57	483
58	138
59	281
60	63
61	108
62	22
63	38
64	75
65	159

n	a(n)
1	9
2	1
3	4
4	5
5	3
6	7
7	12
8	11
9	13
10	42
11	26
12	10
13	17
14	16
15	20
16	82
17	29
18	78
19	57
20	27
21	28
22	66
23	45
24	6
25	69
26	33
27	236
28	40
29	116
30	237
31	196
32	65
33	133
34	90
35	60
36	72
37	80
38	61
39	126
40	24
41	153
42	68
43	88
44	122
45	43
46	156
47	231
48	285
49	125
50	177
51	249
52	106
53	36
54	147
55	23
56	208
57	483
58	138
59	281
60	63
61	108
62	22
63	38
64	75
65	159

n	a(n)
1	9
2	1
3	4
4	5
5	3
6	7
7	12
8	11
9	13
10	42
11	26
12	10
13	17
14	16
15	20
16	82
17	29
18	78
19	57
20	27
21	28
22	66
23	45
24	6
25	69
26	33
27	236
28	40
29	116
30	237
31	196
32	65
33	133
34	90
35	60
36	72
37	80
38	61
39	126
40	24
41	153
42	68
43	88
44	122
45	43
46	156
47	231
48	285
49	125
50	177
51	249
52	106
53	36
54	147
55	23
56	208
57	483
58	138
59	281
60	63
61	108
62	22
63	38
64	75
65	159