A261387 - cp's OEIS frontend

A261387 Number of ways to write n = k + m with 0 < k < m < n such that prime(k) is a primitive root modulo prime(m) and also prime(m) is a primitive root modulo prime(k).

n	a(n)
1	0
2	0
3	1
4	1
5	1
6	1
7	2
8	0
9	2
10	1
11	3
12	3
13	1
14	1
15	2
16	1
17	2
18	7
19	4
20	2
21	1
22	1
23	1
24	4
25	3
26	4
27	2
28	4
29	3
30	3
31	4
32	7
33	3
34	3
35	5
36	5
37	5
38	5
39	4
40	3
41	6
42	7
43	5
44	5
45	5
46	3
47	7
48	7
49	5
50	2
51	7
52	6
53	4
54	5
55	5
56	7
57	10
58	9
59	8
60	8
61	4
62	7
63	5
64	11
65	14
66	7
67	12
68	11
69	9
70	6

[0, 0, 1, 1, 1, 1, 2, 0, 2, 1, 3, 3, 1, 1, 2, 1, 2, 7, 4, 2, 1, 1, 1, 4, 3, 4, 2, 4, 3, 3, 4, 7, 3, 3, 5, 5, 5, 5, 4, 3, 6, 7, 5, 5, 5, 3, 7, 7, 5, 2, 7, 6, 4, 5, 5, 7, 10, 9, 8, 8, 4, 7, 5, 11, 14, 7, 12, 11, 9, 6]

cp's OEIS Frontend

A261387 Number of ways to write n = k + m with 0 < k < m < n such that prime(k) is a primitive root modulo prime(m) and also prime(m) is a primitive root modulo prime(k).

Table of values

List of values

n	a(n)
1	0
2	0
3	1
4	1
5	1
6	1
7	2
8	0
9	2
10	1
11	3
12	3
13	1
14	1
15	2
16	1
17	2
18	7
19	4
20	2
21	1
22	1
23	1
24	4
25	3
26	4
27	2
28	4
29	3
30	3
31	4
32	7
33	3
34	3
35	5
36	5
37	5
38	5
39	4
40	3
41	6
42	7
43	5
44	5
45	5
46	3
47	7
48	7
49	5
50	2
51	7
52	6
53	4
54	5
55	5
56	7
57	10
58	9
59	8
60	8
61	4
62	7
63	5
64	11
65	14
66	7
67	12
68	11
69	9
70	6

n	a(n)
1	0
2	0
3	1
4	1
5	1
6	1
7	2
8	0
9	2
10	1
11	3
12	3
13	1
14	1
15	2
16	1
17	2
18	7
19	4
20	2
21	1
22	1
23	1
24	4
25	3
26	4
27	2
28	4
29	3
30	3
31	4
32	7
33	3
34	3
35	5
36	5
37	5
38	5
39	4
40	3
41	6
42	7
43	5
44	5
45	5
46	3
47	7
48	7
49	5
50	2
51	7
52	6
53	4
54	5
55	5
56	7
57	10
58	9
59	8
60	8
61	4
62	7
63	5
64	11
65	14
66	7
67	12
68	11
69	9
70	6

n	a(n)
1	0
2	0
3	1
4	1
5	1
6	1
7	2
8	0
9	2
10	1
11	3
12	3
13	1
14	1
15	2
16	1
17	2
18	7
19	4
20	2
21	1
22	1
23	1
24	4
25	3
26	4
27	2
28	4
29	3
30	3
31	4
32	7
33	3
34	3
35	5
36	5
37	5
38	5
39	4
40	3
41	6
42	7
43	5
44	5
45	5
46	3
47	7
48	7
49	5
50	2
51	7
52	6
53	4
54	5
55	5
56	7
57	10
58	9
59	8
60	8
61	4
62	7
63	5
64	11
65	14
66	7
67	12
68	11
69	9
70	6