A378288 - cp's OEIS frontend

A378288 Array read by antidiagonals: row k consists of the positive integers j for which the concatenation of 2^k - 1 and 2^j - 1 is prime.

n	a(n)
1	1
2	2
3	1
4	3
5	3
6	1
7	5
8	5
9	2
10	1
11	6
12	9
13	7
14	3
15	1
16	9
17	15
18	10
19	5
20	2
21	1
22	13
23	27
24	11
25	9
26	3
27	7
28	3
29	18
30	45
31	13
32	15
33	6
34	17
35	6
36	1
37	19
38	59
39	14
40	45
41	9
42	41
43	13
44	3
45	2
46	26
47	211
48	25
49	61
50	11
51	101
52	125
53	7
54	5
55	13
56	43
57	303
58	62
59	65
60	13
61	157
62	150
63	9
64	11
65	27
66	3
67	46
68	425
69	70
70	227
71	23
72	367
73	195
74	11
75	14
76	43
77	14
78	11

[1, 2, 1, 3, 3, 1, 5, 5, 2, 1, 6, 9, 7, 3, 1, 9, 15, 10, 5, 2, 1, 13, 27, 11, 9, 3, 7, 3, 18, 45, 13, 15, 6, 17, 6, 1, 19, 59, 14, 45, 9, 41, 13, 3, 2, 26, 211, 25, 61, 11, 101, 125, 7, 5, 13, 43, 303, 62, 65, 13, 157, 150, 9, 11, 27, 3, 46, 425, 70, 227, 23, 367, 195, 11, 14, 43, 14, 11]

cp's OEIS Frontend

A378288 Array read by antidiagonals: row k consists of the positive integers j for which the concatenation of 2^k - 1 and 2^j - 1 is prime.

Table of values

List of values

n	a(n)
1	1
2	2
3	1
4	3
5	3
6	1
7	5
8	5
9	2
10	1
11	6
12	9
13	7
14	3
15	1
16	9
17	15
18	10
19	5
20	2
21	1
22	13
23	27
24	11
25	9
26	3
27	7
28	3
29	18
30	45
31	13
32	15
33	6
34	17
35	6
36	1
37	19
38	59
39	14
40	45
41	9
42	41
43	13
44	3
45	2
46	26
47	211
48	25
49	61
50	11
51	101
52	125
53	7
54	5
55	13
56	43
57	303
58	62
59	65
60	13
61	157
62	150
63	9
64	11
65	27
66	3
67	46
68	425
69	70
70	227
71	23
72	367
73	195
74	11
75	14
76	43
77	14
78	11

n	a(n)
1	1
2	2
3	1
4	3
5	3
6	1
7	5
8	5
9	2
10	1
11	6
12	9
13	7
14	3
15	1
16	9
17	15
18	10
19	5
20	2
21	1
22	13
23	27
24	11
25	9
26	3
27	7
28	3
29	18
30	45
31	13
32	15
33	6
34	17
35	6
36	1
37	19
38	59
39	14
40	45
41	9
42	41
43	13
44	3
45	2
46	26
47	211
48	25
49	61
50	11
51	101
52	125
53	7
54	5
55	13
56	43
57	303
58	62
59	65
60	13
61	157
62	150
63	9
64	11
65	27
66	3
67	46
68	425
69	70
70	227
71	23
72	367
73	195
74	11
75	14
76	43
77	14
78	11

n	a(n)
1	1
2	2
3	1
4	3
5	3
6	1
7	5
8	5
9	2
10	1
11	6
12	9
13	7
14	3
15	1
16	9
17	15
18	10
19	5
20	2
21	1
22	13
23	27
24	11
25	9
26	3
27	7
28	3
29	18
30	45
31	13
32	15
33	6
34	17
35	6
36	1
37	19
38	59
39	14
40	45
41	9
42	41
43	13
44	3
45	2
46	26
47	211
48	25
49	61
50	11
51	101
52	125
53	7
54	5
55	13
56	43
57	303
58	62
59	65
60	13
61	157
62	150
63	9
64	11
65	27
66	3
67	46
68	425
69	70
70	227
71	23
72	367
73	195
74	11
75	14
76	43
77	14
78	11