A226983 - cp's OEIS frontend

A226983 a(n) = ceiling(n/2) - pi(2n) + pi(n-1).

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

[0, -1, 0, 0, 1, 1, 1, 2, 2, 1, 2, 2, 3, 4, 4, 3, 4, 5, 5, 6, 6, 5, 6, 6, 7, 7, 7, 7, 8, 8, 8, 9, 10, 9, 10, 9, 9, 10, 11, 10, 11, 11, 12, 13, 13, 13, 14, 15, 15, 15, 15, 14, 15, 15, 15, 15, 15, 15, 16, 17, 18, 19, 20, 19, 20, 19, 20, 21, 21, 20, 21, 22, 23, 24]

cp's OEIS Frontend

A226983 a(n) = ceiling(n/2) - pi(2n) + pi(n-1).

Table of values

List of values

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

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

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