A379148 - cp's OEIS frontend

A379148 a(n) is the number of iterations of the function x --> 2*x + 1 such that x remains prime, starting from A005384(n).

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

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

cp's OEIS Frontend

A379148 a(n) is the number of iterations of the function x --> 2*x + 1 such that x remains prime, starting from A005384(n).

Table of values

List of values

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

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

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