A229964 - cp's OEIS frontend

A229964 Number of pairs of integers q1, q2 with 1 < q1 < q2 < n such that if we randomly pick an integer in {1, ..., n}, the event of being divisible by q1 is independent of being divisible by q2.

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

[0, 0, 0, 0, 0, 1, 0, 1, 0, 1, 0, 3, 0, 3, 2, 1, 0, 4, 0, 5, 1, 3, 0, 8, 0, 4, 3, 4, 0, 10, 0, 7, 3, 5, 2, 9, 0, 6, 4, 9, 0, 13, 0, 12, 6, 6, 0, 16, 0, 9, 6, 9, 0, 14, 1, 12, 3, 8, 0, 25, 0, 12, 10, 11, 4, 17, 0, 12, 7, 17, 0, 25, 0, 14, 12, 14, 2, 21, 0, 21, 5]

cp's OEIS Frontend

A229964 Number of pairs of integers q1, q2 with 1 < q1 < q2 < n such that if we randomly pick an integer in {1, ..., n}, the event of being divisible by q1 is independent of being divisible by q2.

Table of values

List of values

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

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

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