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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.

A378506 The number of solutions to the equation phi(phi(x)) = n, where phi is the Euler totient function.

Table of values

n a(n)
1 5
2 8
3 0
4 13
5 0
6 4
7 0
8 23
9 0
10 2
11 0
12 14
13 0
14 0
15 0
16 36
17 0
18 2
19 0
20 5
21 0
22 2
23 0
24 32
25 0
26 0
27 0
28 2
29 0
30 0
31 0
32 54
33 0
34 0
35 0
36 11
37 0
38 0
39 0
40 23
41 0
42 0
43 0
44 5
45 0
46 0
47 0
48 66
49 0
50 0
51 0
52 2
53 0
54 4
55 0
56 3
57 0
58 0
59 0
60 2
61 0
62 0
63 0
64 78
65 0
66 0
67 0
68 0
69 0
70 0
71 0
72 38
73 0
74 0
75 0
76 0
77 0
78 0
79 0
80 41
81 0
82 2
83 0
84 6

List of values

[5, 8, 0, 13, 0, 4, 0, 23, 0, 2, 0, 14, 0, 0, 0, 36, 0, 2, 0, 5, 0, 2, 0, 32, 0, 0, 0, 2, 0, 0, 0, 54, 0, 0, 0, 11, 0, 0, 0, 23, 0, 0, 0, 5, 0, 0, 0, 66, 0, 0, 0, 2, 0, 4, 0, 3, 0, 0, 0, 2, 0, 0, 0, 78, 0, 0, 0, 0, 0, 0, 0, 38, 0, 0, 0, 0, 0, 0, 0, 41, 0, 2, 0, 6]

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

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