A239451 - cp's OEIS frontend

A239451 a(n) = |{1 < k < sqrt(n)*log(n): prime(n) + C(prime(k)-1, (prime(k)-1)/2) is prime}|, where C(2j,j) = (2j)!/(j!)^2.

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

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

cp's OEIS Frontend

A239451 a(n) = |{1 < k < sqrt(n)*log(n): prime(n) + C(prime(k)-1, (prime(k)-1)/2) is prime}|, where C(2j,j) = (2j)!/(j!)^2.

Table of values

List of values

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

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

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