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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.

A121556 Numbers such that sigma(n)^2 is divisible by UnitarySigma(n)*UnitaryPhi(n).

Table of values

n a(n)
1 1
2 2
3 3
4 6
5 14
6 15
7 30
8 35
9 42
10 70
11 78
12 105
13 190
14 210
15 348
16 357
17 418
18 570
19 714
20 910
21 1045
22 1144
23 1254
24 2090
25 2296
26 2730
27 3135
28 3432
29 4060
30 4522
31 4674
32 5278
33 6270
34 6888
35 10168
36 10659
37 10824
38 12180
39 12441
40 13566
41 14630
42 15834
43 16770
44 17160

List of values

[1, 2, 3, 6, 14, 15, 30, 35, 42, 70, 78, 105, 190, 210, 348, 357, 418, 570, 714, 910, 1045, 1144, 1254, 2090, 2296, 2730, 3135, 3432, 4060, 4522, 4674, 5278, 6270, 6888, 10168, 10659, 10824, 12180, 12441, 13566, 14630, 15834, 16770, 17160]

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

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