A233547 - cp's OEIS frontend

A233547 a(n) = |{0 < k < n/2: phi(k)phi(n-k) - 1 and phi(k)phi(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	0
6	1
7	2
8	1
9	3
10	4
11	3
12	2
13	3
14	2
15	3
16	1
17	1
18	2
19	1
20	5
21	2
22	3
23	1
24	2
25	1
26	1
27	3
28	4
29	5
30	4
31	3
32	2
33	3
34	2
35	5
36	2
37	5
38	5
39	3
40	5
41	3
42	1
43	5
44	3
45	7
46	6
47	3
48	2
49	4
50	7
51	5
52	1
53	4
54	6
55	6
56	5
57	2
58	4
59	6
60	9
61	9
62	6
63	8
64	5
65	8
66	8
67	6
68	6
69	9
70	4
71	8
72	6
73	8
74	5
75	7
76	9
77	7
78	9
79	5
80	7
81	3
82	9
83	5
84	6
85	7
86	7
87	10
88	5
89	12
90	7
91	5
92	7
93	5
94	7
95	5
96	7
97	8
98	4
99	7
100	13

[0, 0, 0, 0, 0, 1, 2, 1, 3, 4, 3, 2, 3, 2, 3, 1, 1, 2, 1, 5, 2, 3, 1, 2, 1, 1, 3, 4, 5, 4, 3, 2, 3, 2, 5, 2, 5, 5, 3, 5, 3, 1, 5, 3, 7, 6, 3, 2, 4, 7, 5, 1, 4, 6, 6, 5, 2, 4, 6, 9, 9, 6, 8, 5, 8, 8, 6, 6, 9, 4, 8, 6, 8, 5, 7, 9, 7, 9, 5, 7, 3, 9, 5, 6, 7, 7, 10, 5, 12, 7, 5, 7, 5, 7, 5, 7, 8, 4, 7, 13]

cp's OEIS Frontend

A233547 a(n) = |{0 < k < n/2: phi(k)phi(n-k) - 1 and phi(k)phi(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	0
6	1
7	2
8	1
9	3
10	4
11	3
12	2
13	3
14	2
15	3
16	1
17	1
18	2
19	1
20	5
21	2
22	3
23	1
24	2
25	1
26	1
27	3
28	4
29	5
30	4
31	3
32	2
33	3
34	2
35	5
36	2
37	5
38	5
39	3
40	5
41	3
42	1
43	5
44	3
45	7
46	6
47	3
48	2
49	4
50	7
51	5
52	1
53	4
54	6
55	6
56	5
57	2
58	4
59	6
60	9
61	9
62	6
63	8
64	5
65	8
66	8
67	6
68	6
69	9
70	4
71	8
72	6
73	8
74	5
75	7
76	9
77	7
78	9
79	5
80	7
81	3
82	9
83	5
84	6
85	7
86	7
87	10
88	5
89	12
90	7
91	5
92	7
93	5
94	7
95	5
96	7
97	8
98	4
99	7
100	13

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

cp's OEIS Frontend

A233547 a(n) = |{0 < k < n/2: phi(k)*phi(n-k) - 1 and phi(k)*phi(n-k) + 1 are both prime}|, where phi(.) is Euler's totient function.

Table of values

List of values

A233547 a(n) = |{0 < k < n/2: phi(k)phi(n-k) - 1 and phi(k)phi(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	0
6	1
7	2
8	1
9	3
10	4
11	3
12	2
13	3
14	2
15	3
16	1
17	1
18	2
19	1
20	5
21	2
22	3
23	1
24	2
25	1
26	1
27	3
28	4
29	5
30	4
31	3
32	2
33	3
34	2
35	5
36	2
37	5
38	5
39	3
40	5
41	3
42	1
43	5
44	3
45	7
46	6
47	3
48	2
49	4
50	7
51	5
52	1
53	4
54	6
55	6
56	5
57	2
58	4
59	6
60	9
61	9
62	6
63	8
64	5
65	8
66	8
67	6
68	6
69	9
70	4
71	8
72	6
73	8
74	5
75	7
76	9
77	7
78	9
79	5
80	7
81	3
82	9
83	5
84	6
85	7
86	7
87	10
88	5
89	12
90	7
91	5
92	7
93	5
94	7
95	5
96	7
97	8
98	4
99	7
100	13