A236480 - cp's OEIS frontend

A236480 a(n) = |{0 < k < n-2: p = 2*phi(k) + phi(n-k)/2 + 1, prime(p) + 2 and prime(prime(p)) + 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	1
9	1
10	0
11	2
12	1
13	1
14	2
15	1
16	3
17	2
18	2
19	0
20	2
21	3
22	1
23	2
24	1
25	3
26	3
27	2
28	2
29	1
30	1
31	1
32	3
33	0
34	2
35	3
36	2
37	1
38	3
39	0
40	2
41	0
42	1
43	1
44	1
45	1
46	2
47	0
48	0
49	0
50	0
51	2
52	2
53	0
54	1
55	0
56	0
57	0
58	0
59	0
60	0
61	0
62	0
63	1
64	1
65	0
66	1
67	1
68	1
69	0
70	0
71	0
72	0
73	0
74	0
75	0
76	0
77	0
78	0
79	0
80	0
81	0
82	0
83	0
84	0
85	0
86	0
87	0
88	0
89	0
90	0
91	0
92	0
93	0
94	0
95	0
96	0
97	0
98	0
99	0
100	0

[0, 0, 0, 0, 0, 0, 0, 1, 1, 0, 2, 1, 1, 2, 1, 3, 2, 2, 0, 2, 3, 1, 2, 1, 3, 3, 2, 2, 1, 1, 1, 3, 0, 2, 3, 2, 1, 3, 0, 2, 0, 1, 1, 1, 1, 2, 0, 0, 0, 0, 2, 2, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 0, 1, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0]

cp's OEIS Frontend

A236480 a(n) = |{0 < k < n-2: p = 2*phi(k) + phi(n-k)/2 + 1, prime(p) + 2 and prime(prime(p)) + 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	1
9	1
10	0
11	2
12	1
13	1
14	2
15	1
16	3
17	2
18	2
19	0
20	2
21	3
22	1
23	2
24	1
25	3
26	3
27	2
28	2
29	1
30	1
31	1
32	3
33	0
34	2
35	3
36	2
37	1
38	3
39	0
40	2
41	0
42	1
43	1
44	1
45	1
46	2
47	0
48	0
49	0
50	0
51	2
52	2
53	0
54	1
55	0
56	0
57	0
58	0
59	0
60	0
61	0
62	0
63	1
64	1
65	0
66	1
67	1
68	1
69	0
70	0
71	0
72	0
73	0
74	0
75	0
76	0
77	0
78	0
79	0
80	0
81	0
82	0
83	0
84	0
85	0
86	0
87	0
88	0
89	0
90	0
91	0
92	0
93	0
94	0
95	0
96	0
97	0
98	0
99	0
100	0

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

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