A026728 - cp's OEIS frontend

A026728 a(n) = number of primes of the form k*(n-k) + 1.

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

[0, 1, 1, 1, 2, 0, 3, 2, 1, 1, 4, 1, 6, 1, 1, 2, 8, 1, 5, 3, 1, 4, 7, 1, 7, 1, 4, 5, 8, 0, 10, 6, 2, 2, 7, 1, 9, 8, 4, 4, 14, 1, 16, 3, 3, 5, 12, 3, 7, 7, 4, 11, 21, 0, 11, 4, 7, 6, 11, 2, 12, 9, 7, 10, 7, 1, 22, 7, 7, 5, 17, 3, 23, 10, 2, 9, 19, 2, 19, 8, 5, 8, 23, 1, 16, 6, 4, 11, 14, 4, 16, 12, 9, 5, 12]

cp's OEIS Frontend

A026728 a(n) = number of primes of the form k*(n-k) + 1.

Table of values

List of values

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

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

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