A212541 - cp's OEIS frontend

A212541 Let p_n=prime(n), n>=1. Then a(n) is the maximal prime p which differs from p_n, for which the intervals (p/2,p_n/2), (p,p_n], if p or the intervals (p_n/2,p/2), (p_n,p], if p>p_n, contain the same number of primes, and a(n)=0, if no such prime p exists.

n	a(n)
1	0
2	11
3	11
4	11
5	7
6	17
7	13
8	29
9	29
10	23
11	41
12	41
13	37
14	47
15	43
16	59
17	53
18	67
19	61
20	0
21	97
22	97
23	97
24	97
25	89
26	0
27	107
28	103
29	127
30	149
31	109
32	149
33	149
34	151
35	137
36	139
37	167
38	167
39	163
40	179
41	173
42	0
43	227
44	229
45	229
46	233
47	229
48	227
49	223
50	211
51	199
52	0
53	0
54	263
55	263
56	257
57	0
58	281
59	281

[0, 11, 11, 11, 7, 17, 13, 29, 29, 23, 41, 41, 37, 47, 43, 59, 53, 67, 61, 0, 97, 97, 97, 97, 89, 0, 107, 103, 127, 149, 109, 149, 149, 151, 137, 139, 167, 167, 163, 179, 173, 0, 227, 229, 229, 233, 229, 227, 223, 211, 199, 0, 0, 263, 263, 257, 0, 281, 281]

cp's OEIS Frontend

A212541 Let p_n=prime(n), n>=1. Then a(n) is the maximal prime p which differs from p_n, for which the intervals (p/2,p_n/2), (p,p_n], if p or the intervals (p_n/2,p/2), (p_n,p], if p>p_n, contain the same number of primes, and a(n)=0, if no such prime p exists.

Table of values

List of values

n	a(n)
1	0
2	11
3	11
4	11
5	7
6	17
7	13
8	29
9	29
10	23
11	41
12	41
13	37
14	47
15	43
16	59
17	53
18	67
19	61
20	0
21	97
22	97
23	97
24	97
25	89
26	0
27	107
28	103
29	127
30	149
31	109
32	149
33	149
34	151
35	137
36	139
37	167
38	167
39	163
40	179
41	173
42	0
43	227
44	229
45	229
46	233
47	229
48	227
49	223
50	211
51	199
52	0
53	0
54	263
55	263
56	257
57	0
58	281
59	281

n	a(n)
1	0
2	11
3	11
4	11
5	7
6	17
7	13
8	29
9	29
10	23
11	41
12	41
13	37
14	47
15	43
16	59
17	53
18	67
19	61
20	0
21	97
22	97
23	97
24	97
25	89
26	0
27	107
28	103
29	127
30	149
31	109
32	149
33	149
34	151
35	137
36	139
37	167
38	167
39	163
40	179
41	173
42	0
43	227
44	229
45	229
46	233
47	229
48	227
49	223
50	211
51	199
52	0
53	0
54	263
55	263
56	257
57	0
58	281
59	281

n	a(n)
1	0
2	11
3	11
4	11
5	7
6	17
7	13
8	29
9	29
10	23
11	41
12	41
13	37
14	47
15	43
16	59
17	53
18	67
19	61
20	0
21	97
22	97
23	97
24	97
25	89
26	0
27	107
28	103
29	127
30	149
31	109
32	149
33	149
34	151
35	137
36	139
37	167
38	167
39	163
40	179
41	173
42	0
43	227
44	229
45	229
46	233
47	229
48	227
49	223
50	211
51	199
52	0
53	0
54	263
55	263
56	257
57	0
58	281
59	281