A212493 - cp's OEIS frontend

A212493 Let p_n=prime(n), n>=1. Then a(n) is the least 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	5
3	3
4	3
5	3
6	17
7	13
8	23
9	19
10	19
11	37
12	31
13	31
14	47
15	43
16	59
17	53
18	67
19	61
20	0
21	79
22	73
23	73
24	73
25	73
26	0
27	107
28	103
29	127
30	131
31	109
32	113
33	113
34	151
35	113
36	139
37	163
38	157
39	157
40	179
41	173
42	0
43	223
44	197
45	193
46	233
47	193
48	191
49	191
50	193
51	199
52	0
53	0
54	257
55	251
56	251
57	0
58	277
59	271
60	271

[0, 5, 3, 3, 3, 17, 13, 23, 19, 19, 37, 31, 31, 47, 43, 59, 53, 67, 61, 0, 79, 73, 73, 73, 73, 0, 107, 103, 127, 131, 109, 113, 113, 151, 113, 139, 163, 157, 157, 179, 173, 0, 223, 197, 193, 233, 193, 191, 191, 193, 199, 0, 0, 257, 251, 251, 0, 277, 271, 271]

cp's OEIS Frontend

A212493 Let p_n=prime(n), n>=1. Then a(n) is the least 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	5
3	3
4	3
5	3
6	17
7	13
8	23
9	19
10	19
11	37
12	31
13	31
14	47
15	43
16	59
17	53
18	67
19	61
20	0
21	79
22	73
23	73
24	73
25	73
26	0
27	107
28	103
29	127
30	131
31	109
32	113
33	113
34	151
35	113
36	139
37	163
38	157
39	157
40	179
41	173
42	0
43	223
44	197
45	193
46	233
47	193
48	191
49	191
50	193
51	199
52	0
53	0
54	257
55	251
56	251
57	0
58	277
59	271
60	271

n	a(n)
1	0
2	5
3	3
4	3
5	3
6	17
7	13
8	23
9	19
10	19
11	37
12	31
13	31
14	47
15	43
16	59
17	53
18	67
19	61
20	0
21	79
22	73
23	73
24	73
25	73
26	0
27	107
28	103
29	127
30	131
31	109
32	113
33	113
34	151
35	113
36	139
37	163
38	157
39	157
40	179
41	173
42	0
43	223
44	197
45	193
46	233
47	193
48	191
49	191
50	193
51	199
52	0
53	0
54	257
55	251
56	251
57	0
58	277
59	271
60	271

n	a(n)
1	0
2	5
3	3
4	3
5	3
6	17
7	13
8	23
9	19
10	19
11	37
12	31
13	31
14	47
15	43
16	59
17	53
18	67
19	61
20	0
21	79
22	73
23	73
24	73
25	73
26	0
27	107
28	103
29	127
30	131
31	109
32	113
33	113
34	151
35	113
36	139
37	163
38	157
39	157
40	179
41	173
42	0
43	223
44	197
45	193
46	233
47	193
48	191
49	191
50	193
51	199
52	0
53	0
54	257
55	251
56	251
57	0
58	277
59	271
60	271