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.

A121850 Numbers k such that (phi(k) + sigma(k))/rad(k)^2 is an integer, that is (phi(k) + sigma(k)) is divisible by every prime factor of k squared.

Table of values

n a(n)
1 1
2 2
3 588
4 864
5 2430
6 7776
7 27000
8 55296
9 69984
10 82134
11 215622
12 432000
13 497664
14 629856
15 675000
16 862488
17 1499136
18 1749600
19 2187000
20 2667168
21 3449952
22 3538944
23 4287500
24 4312440
25 4478976
26 4563000
27 5668704
28 6912000
29 10800000
30 13045131

List of values

[1, 2, 588, 864, 2430, 7776, 27000, 55296, 69984, 82134, 215622, 432000, 497664, 629856, 675000, 862488, 1499136, 1749600, 2187000, 2667168, 3449952, 3538944, 4287500, 4312440, 4478976, 4563000, 5668704, 6912000, 10800000, 13045131]

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

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