A321211 - cp's OEIS frontend

A321211 Let S be the sequence of integer sets defined by these rules: S(1) = {1}, and for any n > 1, S(n) = {n} U S(pi(n)) U S(n - pi(n)) (where X U Y denotes the union of the sets X and Y and pi is the prime counting function); a(n) = the number of elements of S(n).

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

[1, 2, 3, 3, 4, 4, 5, 4, 6, 6, 6, 7, 7, 7, 8, 7, 8, 9, 9, 9, 9, 8, 10, 9, 10, 11, 11, 11, 11, 12, 12, 12, 11, 12, 11, 12, 13, 13, 13, 14, 14, 14, 13, 14, 14, 14, 15, 14, 14, 12, 14, 15, 14, 15, 16, 17, 17, 16, 16, 16, 16, 17, 16, 16, 17, 17, 16, 16, 15, 17, 19]

cp's OEIS Frontend

A321211 Let S be the sequence of integer sets defined by these rules: S(1) = {1}, and for any n > 1, S(n) = {n} U S(pi(n)) U S(n - pi(n)) (where X U Y denotes the union of the sets X and Y and pi is the prime counting function); a(n) = the number of elements of S(n).

Table of values

List of values

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

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

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