A234308 - cp's OEIS frontend

A234308 a(n) = |{0 < k <= n/2: phi(k^2)*phi(n-k) - 1 is a Sophie Germain prime}|, where phi(.) is Euler's totient function.

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

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

cp's OEIS Frontend

A234308 a(n) = |{0 < k <= n/2: phi(k^2)*phi(n-k) - 1 is a Sophie Germain 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	3
7	1
8	3
9	3
10	1
11	3
12	1
13	2
14	2
15	3
16	2
17	1
18	2
19	1
20	1
21	1
22	2
23	2
24	4
25	3
26	3
27	1
28	2
29	5
30	1
31	2
32	2
33	4
34	1
35	2
36	2
37	3
38	3
39	3
40	3
41	3
42	3
43	7
44	5
45	1
46	4
47	4
48	2
49	3
50	2
51	3
52	2
53	1
54	5
55	1
56	3
57	4
58	2
59	2
60	1
61	2
62	2
63	4
64	4
65	4
66	3
67	5
68	4
69	3
70	2
71	6
72	3
73	6
74	5
75	1
76	6
77	2
78	4
79	3
80	5
81	3
82	4
83	5
84	3
85	4
86	4
87	3
88	6
89	3
90	2
91	6
92	2
93	3
94	6
95	1
96	9
97	3
98	4
99	7
100	3

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

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