A375024 - cp's OEIS frontend

A375024 a(n) is the length of the largest sequence S of distinct integers in the range 1..n such that for any prime number p, any run of consecutive multiples of p in S has length exactly 2, and two consecutive terms in S have some common prime factor.

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

[1, 1, 1, 2, 2, 3, 3, 3, 3, 4, 4, 4, 4, 4, 7, 7, 7, 7, 7, 7, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 13, 13, 16, 16, 16, 16, 19, 19, 19, 19, 19, 19]

cp's OEIS Frontend

A375024 a(n) is the length of the largest sequence S of distinct integers in the range 1..n such that for any prime number p, any run of consecutive multiples of p in S has length exactly 2, and two consecutive terms in S have some common prime factor.

Table of values

List of values

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

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

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