A260821 - cp's OEIS frontend

A260821 Least positive integer k for which n*2^(2^k) + 1 is composite.

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

[5, 1, 2, 2, 1, 1, 3, 1, 2, 2, 1, 1, 2, 1, 3, 1, 1, 2, 1, 1, 1, 3, 1, 2, 3, 1, 3, 3, 1, 1, 1, 1, 1, 2, 1, 1, 5, 1, 2, 1, 1, 1, 2, 1, 2, 1, 1, 4, 2, 1, 1, 1, 1, 1, 1, 1, 2, 3, 1, 2, 1, 1, 1, 2, 1, 1, 2, 1, 2, 2, 1, 1, 2, 1, 1, 1, 1, 3, 2, 1, 1, 1, 1, 2, 1, 1, 2]

cp's OEIS Frontend

A260821 Least positive integer k for which n*2^(2^k) + 1 is composite.

Table of values

List of values

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

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

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