A238646 - cp's OEIS frontend

A238646 Number of primes p < n such that the number of squarefree numbers among 1, ..., n-p is prime.

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

[0, 0, 0, 1, 2, 2, 2, 2, 3, 1, 2, 1, 3, 1, 3, 1, 4, 2, 3, 2, 5, 4, 5, 1, 3, 3, 4, 2, 5, 3, 4, 5, 8, 3, 5, 1, 5, 5, 7, 3, 5, 2, 6, 3, 6, 6, 9, 4, 8, 7, 7, 6, 7, 4, 6, 7, 8, 5, 6, 4, 7, 8, 9, 6, 6, 6, 9, 5, 7, 4, 8, 6, 10, 6, 5, 8, 11, 7, 10, 6]

cp's OEIS Frontend

A238646 Number of primes p < n such that the number of squarefree numbers among 1, ..., n-p is prime.

Table of values

List of values

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

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

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