A304247 - cp's OEIS frontend

A304247 Numbers which yield a prime whenever a '2' is inserted between any single pair of adjacent digits.

n	a(n)
1	0
2	1
3	2
4	3
5	4
6	5
7	6
8	7
9	8
10	9
11	17
12	23
13	27
14	29
15	41
16	51
17	53
18	77
19	81
20	83
21	87
22	89
23	99
24	101
25	113
26	123
27	129
28	131
29	137
30	149
31	183
32	207
33	221
34	243
35	251
36	297
37	303
38	321
39	329
40	357
41	359
42	399
43	401
44	417
45	419
46	429
47	441
48	443
49	453
50	461
51	471
52	473
53	527
54	533
55	581
56	597
57	611
58	621

[0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 17, 23, 27, 29, 41, 51, 53, 77, 81, 83, 87, 89, 99, 101, 113, 123, 129, 131, 137, 149, 183, 207, 221, 243, 251, 297, 303, 321, 329, 357, 359, 399, 401, 417, 419, 429, 441, 443, 453, 461, 471, 473, 527, 533, 581, 597, 611, 621]

cp's OEIS Frontend

A304247 Numbers which yield a prime whenever a '2' is inserted between any single pair of adjacent digits.

Table of values

List of values

n	a(n)
1	0
2	1
3	2
4	3
5	4
6	5
7	6
8	7
9	8
10	9
11	17
12	23
13	27
14	29
15	41
16	51
17	53
18	77
19	81
20	83
21	87
22	89
23	99
24	101
25	113
26	123
27	129
28	131
29	137
30	149
31	183
32	207
33	221
34	243
35	251
36	297
37	303
38	321
39	329
40	357
41	359
42	399
43	401
44	417
45	419
46	429
47	441
48	443
49	453
50	461
51	471
52	473
53	527
54	533
55	581
56	597
57	611
58	621

n	a(n)
1	0
2	1
3	2
4	3
5	4
6	5
7	6
8	7
9	8
10	9
11	17
12	23
13	27
14	29
15	41
16	51
17	53
18	77
19	81
20	83
21	87
22	89
23	99
24	101
25	113
26	123
27	129
28	131
29	137
30	149
31	183
32	207
33	221
34	243
35	251
36	297
37	303
38	321
39	329
40	357
41	359
42	399
43	401
44	417
45	419
46	429
47	441
48	443
49	453
50	461
51	471
52	473
53	527
54	533
55	581
56	597
57	611
58	621

n	a(n)
1	0
2	1
3	2
4	3
5	4
6	5
7	6
8	7
9	8
10	9
11	17
12	23
13	27
14	29
15	41
16	51
17	53
18	77
19	81
20	83
21	87
22	89
23	99
24	101
25	113
26	123
27	129
28	131
29	137
30	149
31	183
32	207
33	221
34	243
35	251
36	297
37	303
38	321
39	329
40	357
41	359
42	399
43	401
44	417
45	419
46	429
47	441
48	443
49	453
50	461
51	471
52	473
53	527
54	533
55	581
56	597
57	611
58	621