A330561 - cp's OEIS frontend

A330561 a(n) = number of primes p <= prime(n) with Delta(p) == 0 (mod 4), where Delta(p) = nextprime(p) - p.

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

[0, 0, 0, 1, 1, 2, 2, 3, 3, 3, 3, 4, 4, 5, 5, 5, 5, 5, 6, 6, 6, 7, 7, 8, 9, 9, 10, 10, 11, 11, 12, 12, 12, 12, 12, 12, 12, 13, 13, 13, 13, 13, 13, 14, 14, 15, 16, 17, 17, 18, 18, 18, 18, 18, 18, 18, 18, 18, 19, 19, 19, 19, 20, 20, 21, 21, 21, 21, 21, 22, 22, 23, 23, 23, 24, 24, 25, 26, 27, 27, 27, 27, 27]

cp's OEIS Frontend

A330561 a(n) = number of primes p <= prime(n) with Delta(p) == 0 (mod 4), where Delta(p) = nextprime(p) - p.

Table of values

List of values

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

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

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