A237657 - cp's OEIS frontend

A237657 a(n) = |{n < m < 2*n: pi(m) and pi(m^2) are both prime}|, where pi(.) is given by A000720.

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

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

cp's OEIS Frontend

A237657 a(n) = |{n < m < 2*n: pi(m) and pi(m^2) are both prime}|, where pi(.) is given by A000720.

Table of values

List of values

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

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

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