A245462 - cp's OEIS frontend

A245462 a(1)=1, then a(n) is the smallest odd k > floor(a(n-1)/2)+1 such that k*2^n+1 is prime.

n	a(n)
1	1
2	3
3	5
4	7
5	11
6	7
7	5
8	13
9	15
10	13
11	9
12	15
13	23
14	39
15	35
16	21
17	21
18	33
19	27
20	25
21	33
22	25
23	45
24	45
25	33
26	27
27	15
28	13
29	23
30	49
31	35
32	43
33	99
34	75
35	59
36	81
37	63
38	63
39	81
40	57
41	99
42	73
43	51
44	27
45	35
46	19
47	27
48	15
49	23
50	27
51	17
52	25
53	51
54	49
55	35
56	27
57	29
58	99
59	71
60	45

[1, 3, 5, 7, 11, 7, 5, 13, 15, 13, 9, 15, 23, 39, 35, 21, 21, 33, 27, 25, 33, 25, 45, 45, 33, 27, 15, 13, 23, 49, 35, 43, 99, 75, 59, 81, 63, 63, 81, 57, 99, 73, 51, 27, 35, 19, 27, 15, 23, 27, 17, 25, 51, 49, 35, 27, 29, 99, 71, 45]

cp's OEIS Frontend

A245462 a(1)=1, then a(n) is the smallest odd k > floor(a(n-1)/2)+1 such that k*2^n+1 is prime.

Table of values

List of values

n	a(n)
1	1
2	3
3	5
4	7
5	11
6	7
7	5
8	13
9	15
10	13
11	9
12	15
13	23
14	39
15	35
16	21
17	21
18	33
19	27
20	25
21	33
22	25
23	45
24	45
25	33
26	27
27	15
28	13
29	23
30	49
31	35
32	43
33	99
34	75
35	59
36	81
37	63
38	63
39	81
40	57
41	99
42	73
43	51
44	27
45	35
46	19
47	27
48	15
49	23
50	27
51	17
52	25
53	51
54	49
55	35
56	27
57	29
58	99
59	71
60	45

n	a(n)
1	1
2	3
3	5
4	7
5	11
6	7
7	5
8	13
9	15
10	13
11	9
12	15
13	23
14	39
15	35
16	21
17	21
18	33
19	27
20	25
21	33
22	25
23	45
24	45
25	33
26	27
27	15
28	13
29	23
30	49
31	35
32	43
33	99
34	75
35	59
36	81
37	63
38	63
39	81
40	57
41	99
42	73
43	51
44	27
45	35
46	19
47	27
48	15
49	23
50	27
51	17
52	25
53	51
54	49
55	35
56	27
57	29
58	99
59	71
60	45

n	a(n)
1	1
2	3
3	5
4	7
5	11
6	7
7	5
8	13
9	15
10	13
11	9
12	15
13	23
14	39
15	35
16	21
17	21
18	33
19	27
20	25
21	33
22	25
23	45
24	45
25	33
26	27
27	15
28	13
29	23
30	49
31	35
32	43
33	99
34	75
35	59
36	81
37	63
38	63
39	81
40	57
41	99
42	73
43	51
44	27
45	35
46	19
47	27
48	15
49	23
50	27
51	17
52	25
53	51
54	49
55	35
56	27
57	29
58	99
59	71
60	45