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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.

A211991 Difference between the arithmetic derivative of n and the sum of proper divisors of n.

Table of values

n a(n)
1 0
2 0
3 0
4 1
5 0
6 -1
7 0
8 5
9 2
10 -1
11 0
12 0
13 0
14 -1
15 -1
16 17
17 0
18 0
19 0
20 2
21 -1
22 -1
23 0
24 8
25 4
26 -1
27 14
28 4
29 0
30 -11
31 0
32 49
33 -1
34 -1
35 -1
36 5
37 0
38 -1
39 -1
40 18
41 0
42 -13
43 0
44 8
45 6
46 -1
47 0
48 36
49 6
50 2
51 -1
52 10
53 0
54 15
55 -1
56 28
57 -1
58 -1
59 0
60 -16
61 0
62 -1
63 10
64 129
65 -1
66 -17
67 0
68 14
69 -1
70 -15
71 0
72 33

List of values

[0, 0, 0, 1, 0, -1, 0, 5, 2, -1, 0, 0, 0, -1, -1, 17, 0, 0, 0, 2, -1, -1, 0, 8, 4, -1, 14, 4, 0, -11, 0, 49, -1, -1, -1, 5, 0, -1, -1, 18, 0, -13, 0, 8, 6, -1, 0, 36, 6, 2, -1, 10, 0, 15, -1, 28, -1, -1, 0, -16, 0, -1, 10, 129, -1, -17, 0, 14, -1, -15, 0, 33]

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