A086668 - cp's OEIS frontend

A086668 Number of divisors d of n such that 2d+1 is a prime.

n	a(n)
1	1
2	2
3	2
4	2
5	2
6	4
7	1
8	3
9	3
10	3
11	2
12	4
13	1
14	3
15	4
16	3
17	1
18	6
19	1
20	4
21	3
22	3
23	2
24	5
25	2
26	3
27	3
28	3
29	2
30	7
31	1
32	3
33	4
34	2
35	3
36	7
37	1
38	2
39	3
40	5
41	2
42	6
43	1
44	4
45	5
46	3
47	1
48	6
49	1
50	4
51	3
52	3
53	2
54	7
55	3
56	5
57	2
58	3
59	1
60	8
61	1
62	2
63	5
64	3
65	3
66	6
67	1
68	3
69	4
70	5
71	1
72	8
73	1
74	3
75	5
76	2
77	2
78	7
79	1
80	5
81	4
82	3
83	2
84	6
85	2
86	3
87	3
88	5
89	2
90	10
91	1
92	3
93	2
94	2
95	3
96	7
97	1
98	4
99	6
100	5

[1, 2, 2, 2, 2, 4, 1, 3, 3, 3, 2, 4, 1, 3, 4, 3, 1, 6, 1, 4, 3, 3, 2, 5, 2, 3, 3, 3, 2, 7, 1, 3, 4, 2, 3, 7, 1, 2, 3, 5, 2, 6, 1, 4, 5, 3, 1, 6, 1, 4, 3, 3, 2, 7, 3, 5, 2, 3, 1, 8, 1, 2, 5, 3, 3, 6, 1, 3, 4, 5, 1, 8, 1, 3, 5, 2, 2, 7, 1, 5, 4, 3, 2, 6, 2, 3, 3, 5, 2, 10, 1, 3, 2, 2, 3, 7, 1, 4, 6, 5]

cp's OEIS Frontend

A086668 Number of divisors d of n such that 2d+1 is a prime.

Table of values

List of values

n	a(n)
1	1
2	2
3	2
4	2
5	2
6	4
7	1
8	3
9	3
10	3
11	2
12	4
13	1
14	3
15	4
16	3
17	1
18	6
19	1
20	4
21	3
22	3
23	2
24	5
25	2
26	3
27	3
28	3
29	2
30	7
31	1
32	3
33	4
34	2
35	3
36	7
37	1
38	2
39	3
40	5
41	2
42	6
43	1
44	4
45	5
46	3
47	1
48	6
49	1
50	4
51	3
52	3
53	2
54	7
55	3
56	5
57	2
58	3
59	1
60	8
61	1
62	2
63	5
64	3
65	3
66	6
67	1
68	3
69	4
70	5
71	1
72	8
73	1
74	3
75	5
76	2
77	2
78	7
79	1
80	5
81	4
82	3
83	2
84	6
85	2
86	3
87	3
88	5
89	2
90	10
91	1
92	3
93	2
94	2
95	3
96	7
97	1
98	4
99	6
100	5

n	a(n)
1	1
2	2
3	2
4	2
5	2
6	4
7	1
8	3
9	3
10	3
11	2
12	4
13	1
14	3
15	4
16	3
17	1
18	6
19	1
20	4
21	3
22	3
23	2
24	5
25	2
26	3
27	3
28	3
29	2
30	7
31	1
32	3
33	4
34	2
35	3
36	7
37	1
38	2
39	3
40	5
41	2
42	6
43	1
44	4
45	5
46	3
47	1
48	6
49	1
50	4
51	3
52	3
53	2
54	7
55	3
56	5
57	2
58	3
59	1
60	8
61	1
62	2
63	5
64	3
65	3
66	6
67	1
68	3
69	4
70	5
71	1
72	8
73	1
74	3
75	5
76	2
77	2
78	7
79	1
80	5
81	4
82	3
83	2
84	6
85	2
86	3
87	3
88	5
89	2
90	10
91	1
92	3
93	2
94	2
95	3
96	7
97	1
98	4
99	6
100	5

n	a(n)
1	1
2	2
3	2
4	2
5	2
6	4
7	1
8	3
9	3
10	3
11	2
12	4
13	1
14	3
15	4
16	3
17	1
18	6
19	1
20	4
21	3
22	3
23	2
24	5
25	2
26	3
27	3
28	3
29	2
30	7
31	1
32	3
33	4
34	2
35	3
36	7
37	1
38	2
39	3
40	5
41	2
42	6
43	1
44	4
45	5
46	3
47	1
48	6
49	1
50	4
51	3
52	3
53	2
54	7
55	3
56	5
57	2
58	3
59	1
60	8
61	1
62	2
63	5
64	3
65	3
66	6
67	1
68	3
69	4
70	5
71	1
72	8
73	1
74	3
75	5
76	2
77	2
78	7
79	1
80	5
81	4
82	3
83	2
84	6
85	2
86	3
87	3
88	5
89	2
90	10
91	1
92	3
93	2
94	2
95	3
96	7
97	1
98	4
99	6
100	5