A234200 - cp's OEIS frontend

A234200 a(n) = |{0 < k < n/2: kphi(n-k) - 1 and kphi(n-k) + 1 are both prime}|, where phi(.) is Euler's totient function.

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

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

cp's OEIS Frontend

A234200 a(n) = |{0 < k < n/2: kphi(n-k) - 1 and kphi(n-k) + 1 are both prime}|, where phi(.) is Euler's totient function.

Table of values

List of values

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

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

cp's OEIS Frontend

A234200 a(n) = |{0 < k < n/2: k*phi(n-k) - 1 and k*phi(n-k) + 1 are both prime}|, where phi(.) is Euler's totient function.

Table of values

List of values

A234200 a(n) = |{0 < k < n/2: kphi(n-k) - 1 and kphi(n-k) + 1 are both prime}|, where phi(.) is Euler's totient function.

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