cp's OEIS Frontend

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.

A058075 Numbers k such that gcd(sigma(k), sigma(k+1)) = 1, where sigma(k) is sum of positive divisors of k.

Table of values

n a(n)
1 1
2 2
3 3
4 4
5 7
6 8
7 9
8 15
9 16
10 18
11 24
12 25
13 31
14 35
15 36
16 48
17 63
18 64
19 72
20 80
21 81
22 97
23 99
24 100
25 120
26 121
27 127
28 128
29 143
30 144
31 162
32 200
33 224
34 225
35 241
36 255
37 256
38 288
39 289
40 323
41 337
42 399
43 400
44 483
45 511
46 512
47 528
48 529
49 575
50 576
51 577
52 578
53 624
54 625
55 675
56 721
57 722
58 728
59 729

List of values

[1, 2, 3, 4, 7, 8, 9, 15, 16, 18, 24, 25, 31, 35, 36, 48, 63, 64, 72, 80, 81, 97, 99, 100, 120, 121, 127, 128, 143, 144, 162, 200, 224, 225, 241, 255, 256, 288, 289, 323, 337, 399, 400, 483, 511, 512, 528, 529, 575, 576, 577, 578, 624, 625, 675, 721, 722, 728, 729]

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

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