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This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

A158973 a(n) = count of numbers k <= n such that all proper divisors of k are divisors of n.

Table of values

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

List of values

[1, 2, 3, 4, 4, 6, 5, 7, 6, 7, 6, 11, 7, 9, 9, 10, 8, 12, 9, 13, 11, 11, 10, 17, 11, 12, 12, 14, 11, 18, 12, 16, 14, 14, 14, 20, 13, 15, 15, 20, 14, 20, 15, 19, 20, 17, 16, 25, 17, 20, 18, 20, 17, 23, 19, 24, 19, 19, 18, 29, 19, 21, 24, 24, 21, 25, 20, 24, 22, 27, 21, 32, 22, 24, 26]

Started in 1964 by Neil J. A. Sloane | Maintained by The OEIS Foundation Inc.

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