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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.

A139555 a(n) = number of prime-powers (including 1) that each are <= n and are coprime to n.

Table of values

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

List of values

[1, 1, 2, 2, 4, 2, 5, 4, 6, 4, 8, 4, 9, 6, 7, 7, 11, 6, 12, 8, 10, 8, 13, 8, 13, 10, 13, 11, 16, 8, 17, 14, 15, 13, 16, 11, 19, 14, 16, 13, 20, 12, 21, 16, 17, 16, 22, 15, 22, 17, 20, 18, 24, 17, 22, 18, 21, 19, 25, 16, 26, 21, 22, 22, 25, 18, 28, 22, 25, 19, 29, 21, 30, 24, 26, 24]

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

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