A088627 - cp's OEIS frontend

A088627 Let 2n = r*s. Then a(n) = number of primes of the form r+s (r= 1 and s = 2n contributes 1 to the count if 2n+1 is prime).

n	a(n)
1	1
2	1
3	2
4	0
5	2
6	2
7	0
8	1
9	2
10	0
11	2
12	1
13	0
14	2
15	4
16	0
17	1
18	2
19	0
20	2
21	4
22	0
23	1
24	1
25	0
26	2
27	1
28	0
29	2
30	4
31	0
32	0
33	2
34	0
35	4
36	2
37	0
38	1
39	4
40	0
41	2
42	2
43	0
44	2
45	3
46	0
47	0
48	1
49	0
50	2
51	4
52	0
53	1
54	2
55	0
56	2
57	2
58	0
59	1
60	3
61	0
62	0
63	2
64	0
65	4
66	3
67	0
68	1
69	3
70	0
71	1
72	0
73	0
74	2
75	3
76	0
77	2
78	2
79	0
80	1
81	2
82	0
83	1
84	3
85	0
86	2
87	2
88	0
89	1
90	3
91	0
92	1
93	1
94	0
95	4
96	2
97	0
98	2
99	4
100	0
101	1
102	2
103	0
104	1
105	8

[1, 1, 2, 0, 2, 2, 0, 1, 2, 0, 2, 1, 0, 2, 4, 0, 1, 2, 0, 2, 4, 0, 1, 1, 0, 2, 1, 0, 2, 4, 0, 0, 2, 0, 4, 2, 0, 1, 4, 0, 2, 2, 0, 2, 3, 0, 0, 1, 0, 2, 4, 0, 1, 2, 0, 2, 2, 0, 1, 3, 0, 0, 2, 0, 4, 3, 0, 1, 3, 0, 1, 0, 0, 2, 3, 0, 2, 2, 0, 1, 2, 0, 1, 3, 0, 2, 2, 0, 1, 3, 0, 1, 1, 0, 4, 2, 0, 2, 4, 0, 1, 2, 0, 1, 8]

cp's OEIS Frontend

A088627 Let 2n = r*s. Then a(n) = number of primes of the form r+s (r= 1 and s = 2n contributes 1 to the count if 2n+1 is prime).

Table of values

List of values

n	a(n)
1	1
2	1
3	2
4	0
5	2
6	2
7	0
8	1
9	2
10	0
11	2
12	1
13	0
14	2
15	4
16	0
17	1
18	2
19	0
20	2
21	4
22	0
23	1
24	1
25	0
26	2
27	1
28	0
29	2
30	4
31	0
32	0
33	2
34	0
35	4
36	2
37	0
38	1
39	4
40	0
41	2
42	2
43	0
44	2
45	3
46	0
47	0
48	1
49	0
50	2
51	4
52	0
53	1
54	2
55	0
56	2
57	2
58	0
59	1
60	3
61	0
62	0
63	2
64	0
65	4
66	3
67	0
68	1
69	3
70	0
71	1
72	0
73	0
74	2
75	3
76	0
77	2
78	2
79	0
80	1
81	2
82	0
83	1
84	3
85	0
86	2
87	2
88	0
89	1
90	3
91	0
92	1
93	1
94	0
95	4
96	2
97	0
98	2
99	4
100	0
101	1
102	2
103	0
104	1
105	8

n	a(n)
1	1
2	1
3	2
4	0
5	2
6	2
7	0
8	1
9	2
10	0
11	2
12	1
13	0
14	2
15	4
16	0
17	1
18	2
19	0
20	2
21	4
22	0
23	1
24	1
25	0
26	2
27	1
28	0
29	2
30	4
31	0
32	0
33	2
34	0
35	4
36	2
37	0
38	1
39	4
40	0
41	2
42	2
43	0
44	2
45	3
46	0
47	0
48	1
49	0
50	2
51	4
52	0
53	1
54	2
55	0
56	2
57	2
58	0
59	1
60	3
61	0
62	0
63	2
64	0
65	4
66	3
67	0
68	1
69	3
70	0
71	1
72	0
73	0
74	2
75	3
76	0
77	2
78	2
79	0
80	1
81	2
82	0
83	1
84	3
85	0
86	2
87	2
88	0
89	1
90	3
91	0
92	1
93	1
94	0
95	4
96	2
97	0
98	2
99	4
100	0
101	1
102	2
103	0
104	1
105	8

n	a(n)
1	1
2	1
3	2
4	0
5	2
6	2
7	0
8	1
9	2
10	0
11	2
12	1
13	0
14	2
15	4
16	0
17	1
18	2
19	0
20	2
21	4
22	0
23	1
24	1
25	0
26	2
27	1
28	0
29	2
30	4
31	0
32	0
33	2
34	0
35	4
36	2
37	0
38	1
39	4
40	0
41	2
42	2
43	0
44	2
45	3
46	0
47	0
48	1
49	0
50	2
51	4
52	0
53	1
54	2
55	0
56	2
57	2
58	0
59	1
60	3
61	0
62	0
63	2
64	0
65	4
66	3
67	0
68	1
69	3
70	0
71	1
72	0
73	0
74	2
75	3
76	0
77	2
78	2
79	0
80	1
81	2
82	0
83	1
84	3
85	0
86	2
87	2
88	0
89	1
90	3
91	0
92	1
93	1
94	0
95	4
96	2
97	0
98	2
99	4
100	0
101	1
102	2
103	0
104	1
105	8