A236138 - cp's OEIS frontend

A236138 a(n) = |{0 < k < n: p = phi(k) + phi(n-k)/3 - 1, prime(p-1) - (p-1) and prime(p-1) - 2*prime((p-1)/2) are all prime}|, where phi(.) is Euler's totient function.

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

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

cp's OEIS Frontend

A236138 a(n) = |{0 < k < n: p = phi(k) + phi(n-k)/3 - 1, prime(p-1) - (p-1) and prime(p-1) - 2*prime((p-1)/2) are all 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	0
7	0
8	0
9	0
10	0
11	0
12	0
13	0
14	1
15	0
16	2
17	0
18	3
19	0
20	1
21	3
22	1
23	4
24	0
25	5
26	2
27	2
28	3
29	4
30	1
31	4
32	2
33	5
34	3
35	1
36	6
37	4
38	3
39	0
40	4
41	5
42	3
43	3
44	4
45	5
46	2
47	4
48	2
49	2
50	4
51	3
52	4
53	1
54	2
55	2
56	3
57	5
58	3
59	0
60	3
61	2
62	4
63	1
64	2
65	2
66	4
67	0
68	4
69	1
70	3
71	3
72	2
73	0
74	4
75	1
76	3
77	2
78	3
79	1
80	5
81	3
82	5
83	1
84	4
85	2
86	3
87	5
88	4
89	4
90	5
91	4
92	1
93	2
94	2
95	3
96	3
97	7
98	3
99	2
100	3

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

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