A108129 - cp's OEIS frontend

A108129 Riesel problem: let k=2n-1; then a(n)=smallest m >= 1 such that k*2^m-1 is prime, or -1 if no such prime exists.

n	a(n)
1	2
2	1
3	2
4	1
5	1
6	2
7	3
8	1
9	2
10	1
11	1
12	4
13	3
14	1
15	4
16	1
17	2
18	2
19	1
20	3
21	2
22	7
23	1
24	4
25	1
26	1
27	2
28	1
29	1
30	12
31	3
32	2
33	4
34	5
35	1
36	2
37	7
38	1
39	2
40	1
41	3
42	2
43	5
44	1
45	4
46	1
47	3
48	2
49	1
50	1
51	10
52	3
53	2
54	10
55	9
56	2
57	8
58	1
59	1
60	12
61	1
62	2
63	2
64	25
65	1
66	2
67	3
68	1
69	2
70	1
71	1
72	2
73	5
74	1
75	4
76	5
77	3
78	2
79	1
80	1
81	2
82	3
83	2
84	4
85	1
86	2
87	2
88	1
89	1
90	8
91	3
92	4
93	2
94	1
95	3
96	226
97	3
98	1
99	2
100	1
101	1
102	2

[2, 1, 2, 1, 1, 2, 3, 1, 2, 1, 1, 4, 3, 1, 4, 1, 2, 2, 1, 3, 2, 7, 1, 4, 1, 1, 2, 1, 1, 12, 3, 2, 4, 5, 1, 2, 7, 1, 2, 1, 3, 2, 5, 1, 4, 1, 3, 2, 1, 1, 10, 3, 2, 10, 9, 2, 8, 1, 1, 12, 1, 2, 2, 25, 1, 2, 3, 1, 2, 1, 1, 2, 5, 1, 4, 5, 3, 2, 1, 1, 2, 3, 2, 4, 1, 2, 2, 1, 1, 8, 3, 4, 2, 1, 3, 226, 3, 1, 2, 1, 1, 2]

cp's OEIS Frontend

A108129 Riesel problem: let k=2n-1; then a(n)=smallest m >= 1 such that k*2^m-1 is prime, or -1 if no such prime exists.

Table of values

List of values

n	a(n)
1	2
2	1
3	2
4	1
5	1
6	2
7	3
8	1
9	2
10	1
11	1
12	4
13	3
14	1
15	4
16	1
17	2
18	2
19	1
20	3
21	2
22	7
23	1
24	4
25	1
26	1
27	2
28	1
29	1
30	12
31	3
32	2
33	4
34	5
35	1
36	2
37	7
38	1
39	2
40	1
41	3
42	2
43	5
44	1
45	4
46	1
47	3
48	2
49	1
50	1
51	10
52	3
53	2
54	10
55	9
56	2
57	8
58	1
59	1
60	12
61	1
62	2
63	2
64	25
65	1
66	2
67	3
68	1
69	2
70	1
71	1
72	2
73	5
74	1
75	4
76	5
77	3
78	2
79	1
80	1
81	2
82	3
83	2
84	4
85	1
86	2
87	2
88	1
89	1
90	8
91	3
92	4
93	2
94	1
95	3
96	226
97	3
98	1
99	2
100	1
101	1
102	2

n	a(n)
1	2
2	1
3	2
4	1
5	1
6	2
7	3
8	1
9	2
10	1
11	1
12	4
13	3
14	1
15	4
16	1
17	2
18	2
19	1
20	3
21	2
22	7
23	1
24	4
25	1
26	1
27	2
28	1
29	1
30	12
31	3
32	2
33	4
34	5
35	1
36	2
37	7
38	1
39	2
40	1
41	3
42	2
43	5
44	1
45	4
46	1
47	3
48	2
49	1
50	1
51	10
52	3
53	2
54	10
55	9
56	2
57	8
58	1
59	1
60	12
61	1
62	2
63	2
64	25
65	1
66	2
67	3
68	1
69	2
70	1
71	1
72	2
73	5
74	1
75	4
76	5
77	3
78	2
79	1
80	1
81	2
82	3
83	2
84	4
85	1
86	2
87	2
88	1
89	1
90	8
91	3
92	4
93	2
94	1
95	3
96	226
97	3
98	1
99	2
100	1
101	1
102	2

n	a(n)
1	2
2	1
3	2
4	1
5	1
6	2
7	3
8	1
9	2
10	1
11	1
12	4
13	3
14	1
15	4
16	1
17	2
18	2
19	1
20	3
21	2
22	7
23	1
24	4
25	1
26	1
27	2
28	1
29	1
30	12
31	3
32	2
33	4
34	5
35	1
36	2
37	7
38	1
39	2
40	1
41	3
42	2
43	5
44	1
45	4
46	1
47	3
48	2
49	1
50	1
51	10
52	3
53	2
54	10
55	9
56	2
57	8
58	1
59	1
60	12
61	1
62	2
63	2
64	25
65	1
66	2
67	3
68	1
69	2
70	1
71	1
72	2
73	5
74	1
75	4
76	5
77	3
78	2
79	1
80	1
81	2
82	3
83	2
84	4
85	1
86	2
87	2
88	1
89	1
90	8
91	3
92	4
93	2
94	1
95	3
96	226
97	3
98	1
99	2
100	1
101	1
102	2