A235805 - cp's OEIS frontend

A235805 a(n) = |{0 < k < n - 2: 2m + 1, m(m+1) - prime(m) and m*(m+1) - prime(m+1) are all prime with m = phi(k) + phi(n-k)/2}|, where phi(.) is Euler's totient function.

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

[0, 0, 0, 0, 0, 2, 3, 2, 4, 4, 4, 4, 4, 4, 2, 6, 3, 7, 4, 2, 7, 3, 5, 4, 4, 6, 6, 6, 4, 4, 7, 8, 9, 6, 6, 11, 8, 10, 6, 6, 12, 8, 13, 6, 12, 8, 13, 10, 7, 14, 10, 11, 11, 11, 16, 14, 13, 9, 15, 11, 23, 14, 12, 11, 12, 10, 14, 8, 15, 9, 14, 13, 11, 12, 9, 19, 9, 14, 11, 16, 8, 14, 5, 13, 8, 13, 9, 13, 10, 15, 10, 11, 12, 17, 8, 13, 10, 11, 7, 18]

cp's OEIS Frontend

A235805 a(n) = |{0 < k < n - 2: 2m + 1, m(m+1) - prime(m) and m*(m+1) - prime(m+1) are all prime with m = phi(k) + phi(n-k)/2}|, 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	2
7	3
8	2
9	4
10	4
11	4
12	4
13	4
14	4
15	2
16	6
17	3
18	7
19	4
20	2
21	7
22	3
23	5
24	4
25	4
26	6
27	6
28	6
29	4
30	4
31	7
32	8
33	9
34	6
35	6
36	11
37	8
38	10
39	6
40	6
41	12
42	8
43	13
44	6
45	12
46	8
47	13
48	10
49	7
50	14
51	10
52	11
53	11
54	11
55	16
56	14
57	13
58	9
59	15
60	11
61	23
62	14
63	12
64	11
65	12
66	10
67	14
68	8
69	15
70	9
71	14
72	13
73	11
74	12
75	9
76	19
77	9
78	14
79	11
80	16
81	8
82	14
83	5
84	13
85	8
86	13
87	9
88	13
89	10
90	15
91	10
92	11
93	12
94	17
95	8
96	13
97	10
98	11
99	7
100	18

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

cp's OEIS Frontend

A235805 a(n) = |{0 < k < n - 2: 2*m + 1, m*(m+1) - prime(m) and m*(m+1) - prime(m+1) are all prime with m = phi(k) + phi(n-k)/2}|, where phi(.) is Euler's totient function.

Table of values

List of values

A235805 a(n) = |{0 < k < n - 2: 2m + 1, m(m+1) - prime(m) and m*(m+1) - prime(m+1) are all prime with m = phi(k) + phi(n-k)/2}|, where phi(.) is Euler's totient function.

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