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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.

A227758 a(n) = sigma(sigma(n)) - sigma(n) - n, where sigma(n) = A000203(n) = sum of the divisors of n.

Table of values

n a(n)
1 -1
2 -1
3 0
4 -3
5 1
6 10
7 0
8 1
9 -8
10 11
11 5
12 16
13 -3
14 22
15 21
16 -15
17 4
18 -1
19 3
20 34
21 10
22 33
23 13
24 84
25 -24
26 28
27 23
28 36
29 13
30 93
31 0
32 9
33 43
34 32
35 41
36 -15
37 -15
38 70
39 25
40 104
41 13
42 114
43 -3
44 96
45 45
46 77
47 29
48 52
49 -26
50 -15
51 72
52 21
53 13
54 186
55 68
56 184
57 49
58 86
59 49
60 252
61 -27
62 94
63 43
64 -63

List of values

[-1, -1, 0, -3, 1, 10, 0, 1, -8, 11, 5, 16, -3, 22, 21, -15, 4, -1, 3, 34, 10, 33, 13, 84, -24, 28, 23, 36, 13, 93, 0, 9, 43, 32, 41, -15, -15, 70, 25, 104, 13, 114, -3, 96, 45, 77, 29, 52, -26, -15, 72, 21, 13, 186, 68, 184, 49, 86, 49, 252, -27, 94, 43, -63]

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

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