A356190 - cp's OEIS frontend

A356190 a(n) is the least prime p such that there are exactly n primes strictly between p and 2*p, or -1 if there is no such p.

n	a(n)
1	2
2	7
3	11
4	17
5	23
6	29
7	31
8	-1
9	37
10	-1
11	53
12	61
13	59
14	71
15	79
16	89
17	-1
18	109
19	97
20	101
21	-1
22	-1
23	127
24	-1
25	137
26	151
27	149
28	157
29	-1
30	179
31	-1
32	191
33	-1
34	-1
35	211
36	-1
37	-1
38	223
39	233
40	-1
41	251
42	257
43	263
44	293
45	-1
46	-1
47	-1
48	-1
49	307
50	311
51	-1
52	-1
53	-1
54	331
55	349
56	347
57	367
58	373
59	379
60	389
61	409
62	-1
63	-1
64	419
65	-1
66	431
67	443

[2, 7, 11, 17, 23, 29, 31, -1, 37, -1, 53, 61, 59, 71, 79, 89, -1, 109, 97, 101, -1, -1, 127, -1, 137, 151, 149, 157, -1, 179, -1, 191, -1, -1, 211, -1, -1, 223, 233, -1, 251, 257, 263, 293, -1, -1, -1, -1, 307, 311, -1, -1, -1, 331, 349, 347, 367, 373, 379, 389, 409, -1, -1, 419, -1, 431, 443]

cp's OEIS Frontend

A356190 a(n) is the least prime p such that there are exactly n primes strictly between p and 2*p, or -1 if there is no such p.

Table of values

List of values

n	a(n)
1	2
2	7
3	11
4	17
5	23
6	29
7	31
8	-1
9	37
10	-1
11	53
12	61
13	59
14	71
15	79
16	89
17	-1
18	109
19	97
20	101
21	-1
22	-1
23	127
24	-1
25	137
26	151
27	149
28	157
29	-1
30	179
31	-1
32	191
33	-1
34	-1
35	211
36	-1
37	-1
38	223
39	233
40	-1
41	251
42	257
43	263
44	293
45	-1
46	-1
47	-1
48	-1
49	307
50	311
51	-1
52	-1
53	-1
54	331
55	349
56	347
57	367
58	373
59	379
60	389
61	409
62	-1
63	-1
64	419
65	-1
66	431
67	443

n	a(n)
1	2
2	7
3	11
4	17
5	23
6	29
7	31
8	-1
9	37
10	-1
11	53
12	61
13	59
14	71
15	79
16	89
17	-1
18	109
19	97
20	101
21	-1
22	-1
23	127
24	-1
25	137
26	151
27	149
28	157
29	-1
30	179
31	-1
32	191
33	-1
34	-1
35	211
36	-1
37	-1
38	223
39	233
40	-1
41	251
42	257
43	263
44	293
45	-1
46	-1
47	-1
48	-1
49	307
50	311
51	-1
52	-1
53	-1
54	331
55	349
56	347
57	367
58	373
59	379
60	389
61	409
62	-1
63	-1
64	419
65	-1
66	431
67	443

n	a(n)
1	2
2	7
3	11
4	17
5	23
6	29
7	31
8	-1
9	37
10	-1
11	53
12	61
13	59
14	71
15	79
16	89
17	-1
18	109
19	97
20	101
21	-1
22	-1
23	127
24	-1
25	137
26	151
27	149
28	157
29	-1
30	179
31	-1
32	191
33	-1
34	-1
35	211
36	-1
37	-1
38	223
39	233
40	-1
41	251
42	257
43	263
44	293
45	-1
46	-1
47	-1
48	-1
49	307
50	311
51	-1
52	-1
53	-1
54	331
55	349
56	347
57	367
58	373
59	379
60	389
61	409
62	-1
63	-1
64	419
65	-1
66	431
67	443