A249806 - cp's OEIS frontend

A249806 Smallest odd number k>1 such that k*2^prime(n)-1 is also prime.

n	a(n)
1	3
2	3
3	7
4	3
5	3
6	9
7	7
8	51
9	13
10	7
11	15
12	21
13	15
14	3
15	31
16	147
17	45
18	69
19	43
20	73
21	15
22	69
23	91
24	19
25	51
26	81
27	3
28	25
29	9
30	85
31	103
32	55
33	169
34	225
35	109
36	145
37	15
38	103
39	615
40	69
41	259
42	69
43	63
44	45
45	285
46	471
47	9
48	255
49	169
50	489
51	69
52	273
53	427
54	43
55	391
56	169
57	201
58	21

[3, 3, 7, 3, 3, 9, 7, 51, 13, 7, 15, 21, 15, 3, 31, 147, 45, 69, 43, 73, 15, 69, 91, 19, 51, 81, 3, 25, 9, 85, 103, 55, 169, 225, 109, 145, 15, 103, 615, 69, 259, 69, 63, 45, 285, 471, 9, 255, 169, 489, 69, 273, 427, 43, 391, 169, 201, 21]

cp's OEIS Frontend

A249806 Smallest odd number k>1 such that k*2^prime(n)-1 is also prime.

Table of values

List of values

n	a(n)
1	3
2	3
3	7
4	3
5	3
6	9
7	7
8	51
9	13
10	7
11	15
12	21
13	15
14	3
15	31
16	147
17	45
18	69
19	43
20	73
21	15
22	69
23	91
24	19
25	51
26	81
27	3
28	25
29	9
30	85
31	103
32	55
33	169
34	225
35	109
36	145
37	15
38	103
39	615
40	69
41	259
42	69
43	63
44	45
45	285
46	471
47	9
48	255
49	169
50	489
51	69
52	273
53	427
54	43
55	391
56	169
57	201
58	21

n	a(n)
1	3
2	3
3	7
4	3
5	3
6	9
7	7
8	51
9	13
10	7
11	15
12	21
13	15
14	3
15	31
16	147
17	45
18	69
19	43
20	73
21	15
22	69
23	91
24	19
25	51
26	81
27	3
28	25
29	9
30	85
31	103
32	55
33	169
34	225
35	109
36	145
37	15
38	103
39	615
40	69
41	259
42	69
43	63
44	45
45	285
46	471
47	9
48	255
49	169
50	489
51	69
52	273
53	427
54	43
55	391
56	169
57	201
58	21

n	a(n)
1	3
2	3
3	7
4	3
5	3
6	9
7	7
8	51
9	13
10	7
11	15
12	21
13	15
14	3
15	31
16	147
17	45
18	69
19	43
20	73
21	15
22	69
23	91
24	19
25	51
26	81
27	3
28	25
29	9
30	85
31	103
32	55
33	169
34	225
35	109
36	145
37	15
38	103
39	615
40	69
41	259
42	69
43	63
44	45
45	285
46	471
47	9
48	255
49	169
50	489
51	69
52	273
53	427
54	43
55	391
56	169
57	201
58	21