A156770 - cp's OEIS frontend

A156770 1 followed by least greater integer such that concatenation of a(n-1) and a(n) is prime.

n	a(n)
1	1
2	3
3	7
4	9
5	11
6	17
7	21
8	29
9	39
10	43
11	49
12	51
13	53
14	81
15	91
16	99
17	103
18	123
19	127
20	133
21	153
22	191
23	227
24	231
25	241
26	249
27	253
28	273
29	281
30	291
31	293
32	311
33	323
34	333
35	337
36	339
37	341
38	347
39	359
40	377
41	387
42	397
43	427
44	429
45	431
46	441
47	443
48	453
49	461
50	467
51	471
52	481
53	489
54	493
55	523
56	541

[1, 3, 7, 9, 11, 17, 21, 29, 39, 43, 49, 51, 53, 81, 91, 99, 103, 123, 127, 133, 153, 191, 227, 231, 241, 249, 253, 273, 281, 291, 293, 311, 323, 333, 337, 339, 341, 347, 359, 377, 387, 397, 427, 429, 431, 441, 443, 453, 461, 467, 471, 481, 489, 493, 523, 541]

cp's OEIS Frontend

A156770 1 followed by least greater integer such that concatenation of a(n-1) and a(n) is prime.

Table of values

List of values

n	a(n)
1	1
2	3
3	7
4	9
5	11
6	17
7	21
8	29
9	39
10	43
11	49
12	51
13	53
14	81
15	91
16	99
17	103
18	123
19	127
20	133
21	153
22	191
23	227
24	231
25	241
26	249
27	253
28	273
29	281
30	291
31	293
32	311
33	323
34	333
35	337
36	339
37	341
38	347
39	359
40	377
41	387
42	397
43	427
44	429
45	431
46	441
47	443
48	453
49	461
50	467
51	471
52	481
53	489
54	493
55	523
56	541

n	a(n)
1	1
2	3
3	7
4	9
5	11
6	17
7	21
8	29
9	39
10	43
11	49
12	51
13	53
14	81
15	91
16	99
17	103
18	123
19	127
20	133
21	153
22	191
23	227
24	231
25	241
26	249
27	253
28	273
29	281
30	291
31	293
32	311
33	323
34	333
35	337
36	339
37	341
38	347
39	359
40	377
41	387
42	397
43	427
44	429
45	431
46	441
47	443
48	453
49	461
50	467
51	471
52	481
53	489
54	493
55	523
56	541

n	a(n)
1	1
2	3
3	7
4	9
5	11
6	17
7	21
8	29
9	39
10	43
11	49
12	51
13	53
14	81
15	91
16	99
17	103
18	123
19	127
20	133
21	153
22	191
23	227
24	231
25	241
26	249
27	253
28	273
29	281
30	291
31	293
32	311
33	323
34	333
35	337
36	339
37	341
38	347
39	359
40	377
41	387
42	397
43	427
44	429
45	431
46	441
47	443
48	453
49	461
50	467
51	471
52	481
53	489
54	493
55	523
56	541