A267098 - cp's OEIS frontend

A267098 a(n) = number of 4k+3 primes among first n primes; least monotonic left inverse of A080148.

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

[0, 1, 1, 2, 3, 3, 3, 4, 5, 5, 6, 6, 6, 7, 8, 8, 9, 9, 10, 11, 11, 12, 13, 13, 13, 13, 14, 15, 15, 15, 16, 17, 17, 18, 18, 19, 19, 20, 21, 21, 22, 22, 23, 23, 23, 24, 25, 26, 27, 27, 27, 28, 28, 29, 29, 30, 30, 31, 31, 31, 32, 32, 33, 34, 34, 34, 35, 35, 36, 36, 36, 37, 38, 38, 39, 40, 40, 40, 40, 40, 41, 41, 42]

cp's OEIS Frontend

A267098 a(n) = number of 4k+3 primes among first n primes; least monotonic left inverse of A080148.

Table of values

List of values

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

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

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