A234399 - cp's OEIS frontend

A234399 a(n) = |{0 < k < n: 2^k*(2^phi(n-k) - 1) + 1 is prime}|, where phi(.) is Euler's totient function.

n	a(n)
1	0
2	1
3	2
4	2
5	3
6	3
7	2
8	3
9	5
10	4
11	4
12	5
13	3
14	6
15	5
16	3
17	6
18	8
19	4
20	5
21	5
22	6
23	4
24	6
25	7
26	4
27	5
28	6
29	4
30	3
31	4
32	9
33	5
34	3
35	8
36	5
37	4
38	3
39	8
40	8
41	3
42	8
43	6
44	7
45	7
46	8
47	8
48	9
49	4
50	5
51	8
52	9
53	7
54	6
55	10
56	11
57	4
58	6
59	6
60	8
61	8
62	10
63	4
64	4
65	7
66	4
67	12
68	8
69	6
70	4
71	9
72	7
73	4
74	6
75	10
76	9
77	8
78	7
79	7
80	7
81	5
82	4
83	10
84	5
85	6
86	7
87	9
88	15
89	7
90	8
91	10
92	7
93	4
94	8
95	6
96	10
97	3
98	3
99	10
100	11

[0, 1, 2, 2, 3, 3, 2, 3, 5, 4, 4, 5, 3, 6, 5, 3, 6, 8, 4, 5, 5, 6, 4, 6, 7, 4, 5, 6, 4, 3, 4, 9, 5, 3, 8, 5, 4, 3, 8, 8, 3, 8, 6, 7, 7, 8, 8, 9, 4, 5, 8, 9, 7, 6, 10, 11, 4, 6, 6, 8, 8, 10, 4, 4, 7, 4, 12, 8, 6, 4, 9, 7, 4, 6, 10, 9, 8, 7, 7, 7, 5, 4, 10, 5, 6, 7, 9, 15, 7, 8, 10, 7, 4, 8, 6, 10, 3, 3, 10, 11]

cp's OEIS Frontend

A234399 a(n) = |{0 < k < n: 2^k*(2^phi(n-k) - 1) + 1 is prime}|, where phi(.) is Euler's totient function.

Table of values

List of values

n	a(n)
1	0
2	1
3	2
4	2
5	3
6	3
7	2
8	3
9	5
10	4
11	4
12	5
13	3
14	6
15	5
16	3
17	6
18	8
19	4
20	5
21	5
22	6
23	4
24	6
25	7
26	4
27	5
28	6
29	4
30	3
31	4
32	9
33	5
34	3
35	8
36	5
37	4
38	3
39	8
40	8
41	3
42	8
43	6
44	7
45	7
46	8
47	8
48	9
49	4
50	5
51	8
52	9
53	7
54	6
55	10
56	11
57	4
58	6
59	6
60	8
61	8
62	10
63	4
64	4
65	7
66	4
67	12
68	8
69	6
70	4
71	9
72	7
73	4
74	6
75	10
76	9
77	8
78	7
79	7
80	7
81	5
82	4
83	10
84	5
85	6
86	7
87	9
88	15
89	7
90	8
91	10
92	7
93	4
94	8
95	6
96	10
97	3
98	3
99	10
100	11

n	a(n)
1	0
2	1
3	2
4	2
5	3
6	3
7	2
8	3
9	5
10	4
11	4
12	5
13	3
14	6
15	5
16	3
17	6
18	8
19	4
20	5
21	5
22	6
23	4
24	6
25	7
26	4
27	5
28	6
29	4
30	3
31	4
32	9
33	5
34	3
35	8
36	5
37	4
38	3
39	8
40	8
41	3
42	8
43	6
44	7
45	7
46	8
47	8
48	9
49	4
50	5
51	8
52	9
53	7
54	6
55	10
56	11
57	4
58	6
59	6
60	8
61	8
62	10
63	4
64	4
65	7
66	4
67	12
68	8
69	6
70	4
71	9
72	7
73	4
74	6
75	10
76	9
77	8
78	7
79	7
80	7
81	5
82	4
83	10
84	5
85	6
86	7
87	9
88	15
89	7
90	8
91	10
92	7
93	4
94	8
95	6
96	10
97	3
98	3
99	10
100	11

n	a(n)
1	0
2	1
3	2
4	2
5	3
6	3
7	2
8	3
9	5
10	4
11	4
12	5
13	3
14	6
15	5
16	3
17	6
18	8
19	4
20	5
21	5
22	6
23	4
24	6
25	7
26	4
27	5
28	6
29	4
30	3
31	4
32	9
33	5
34	3
35	8
36	5
37	4
38	3
39	8
40	8
41	3
42	8
43	6
44	7
45	7
46	8
47	8
48	9
49	4
50	5
51	8
52	9
53	7
54	6
55	10
56	11
57	4
58	6
59	6
60	8
61	8
62	10
63	4
64	4
65	7
66	4
67	12
68	8
69	6
70	4
71	9
72	7
73	4
74	6
75	10
76	9
77	8
78	7
79	7
80	7
81	5
82	4
83	10
84	5
85	6
86	7
87	9
88	15
89	7
90	8
91	10
92	7
93	4
94	8
95	6
96	10
97	3
98	3
99	10
100	11