A026233 - cp's OEIS frontend

A026233 a(n) = j if n is the j-th prime, else a(n) = k if n is the k-th nonprime.

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

[1, 1, 2, 2, 3, 3, 4, 4, 5, 6, 5, 7, 6, 8, 9, 10, 7, 11, 8, 12, 13, 14, 9, 15, 16, 17, 18, 19, 10, 20, 11, 21, 22, 23, 24, 25, 12, 26, 27, 28, 13, 29, 14, 30, 31, 32, 15, 33, 34, 35, 36, 37, 16, 38, 39, 40, 41, 42, 17, 43, 18, 44, 45, 46, 47, 48]

cp's OEIS Frontend

A026233 a(n) = j if n is the j-th prime, else a(n) = k if n is the k-th nonprime.

Table of values

List of values

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

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

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