A039640 - cp's OEIS frontend

A039640 Fixed point of "k -> k/2 or (k+1)/2 until result is prime", starting with prime(n)-1.

n	a(n)
1	1
2	2
3	2
4	3
5	5
6	3
7	2
8	5
9	11
10	7
11	2
12	5
13	5
14	11
15	23
16	13
17	29
18	2
19	17
20	5
21	5
22	5
23	41
24	11
25	3
26	13
27	13
28	53
29	7
30	7
31	2
32	17
33	17
34	5
35	37
36	19
37	5
38	41
39	83
40	43
41	89
42	23
43	3
44	3
45	13
46	13
47	53
48	7
49	113
50	29
51	29
52	2
53	2
54	2
55	2
56	131
57	67
58	17
59	5
60	5
61	71
62	73
63	5
64	5
65	5
66	79
67	83
68	11
69	173
70	11
71	11
72	179
73	23
74	47
75	3
76	191
77	97
78	13

[1, 2, 2, 3, 5, 3, 2, 5, 11, 7, 2, 5, 5, 11, 23, 13, 29, 2, 17, 5, 5, 5, 41, 11, 3, 13, 13, 53, 7, 7, 2, 17, 17, 5, 37, 19, 5, 41, 83, 43, 89, 23, 3, 3, 13, 13, 53, 7, 113, 29, 29, 2, 2, 2, 2, 131, 67, 17, 5, 5, 71, 73, 5, 5, 5, 79, 83, 11, 173, 11, 11, 179, 23, 47, 3, 191, 97, 13]

cp's OEIS Frontend

A039640 Fixed point of "k -> k/2 or (k+1)/2 until result is prime", starting with prime(n)-1.

Table of values

List of values

n	a(n)
1	1
2	2
3	2
4	3
5	5
6	3
7	2
8	5
9	11
10	7
11	2
12	5
13	5
14	11
15	23
16	13
17	29
18	2
19	17
20	5
21	5
22	5
23	41
24	11
25	3
26	13
27	13
28	53
29	7
30	7
31	2
32	17
33	17
34	5
35	37
36	19
37	5
38	41
39	83
40	43
41	89
42	23
43	3
44	3
45	13
46	13
47	53
48	7
49	113
50	29
51	29
52	2
53	2
54	2
55	2
56	131
57	67
58	17
59	5
60	5
61	71
62	73
63	5
64	5
65	5
66	79
67	83
68	11
69	173
70	11
71	11
72	179
73	23
74	47
75	3
76	191
77	97
78	13

n	a(n)
1	1
2	2
3	2
4	3
5	5
6	3
7	2
8	5
9	11
10	7
11	2
12	5
13	5
14	11
15	23
16	13
17	29
18	2
19	17
20	5
21	5
22	5
23	41
24	11
25	3
26	13
27	13
28	53
29	7
30	7
31	2
32	17
33	17
34	5
35	37
36	19
37	5
38	41
39	83
40	43
41	89
42	23
43	3
44	3
45	13
46	13
47	53
48	7
49	113
50	29
51	29
52	2
53	2
54	2
55	2
56	131
57	67
58	17
59	5
60	5
61	71
62	73
63	5
64	5
65	5
66	79
67	83
68	11
69	173
70	11
71	11
72	179
73	23
74	47
75	3
76	191
77	97
78	13

n	a(n)
1	1
2	2
3	2
4	3
5	5
6	3
7	2
8	5
9	11
10	7
11	2
12	5
13	5
14	11
15	23
16	13
17	29
18	2
19	17
20	5
21	5
22	5
23	41
24	11
25	3
26	13
27	13
28	53
29	7
30	7
31	2
32	17
33	17
34	5
35	37
36	19
37	5
38	41
39	83
40	43
41	89
42	23
43	3
44	3
45	13
46	13
47	53
48	7
49	113
50	29
51	29
52	2
53	2
54	2
55	2
56	131
57	67
58	17
59	5
60	5
61	71
62	73
63	5
64	5
65	5
66	79
67	83
68	11
69	173
70	11
71	11
72	179
73	23
74	47
75	3
76	191
77	97
78	13