A331677 - cp's OEIS frontend

A331677 a(n) is the difference between the number of primes smaller than prime(n) (i.e., n-1) and greater than prime(n) but less than 2*prime(n).

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

[-1, 0, 1, 1, 1, 2, 2, 3, 3, 3, 3, 2, 3, 4, 5, 4, 3, 5, 5, 5, 7, 6, 7, 7, 5, 5, 7, 8, 10, 11, 7, 8, 7, 8, 7, 9, 8, 9, 10, 11, 10, 11, 10, 11, 12, 13, 11, 9, 10, 11, 11, 12, 13, 12, 12, 12, 14, 15, 16, 17, 18, 17, 13, 13, 15, 16, 12, 13, 12, 14, 15, 16, 15, 15]

cp's OEIS Frontend

A331677 a(n) is the difference between the number of primes smaller than prime(n) (i.e., n-1) and greater than prime(n) but less than 2*prime(n).

Table of values

List of values

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

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

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