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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.

A243018 Numbers k such that Sum_{i=1..k} phi(i) is divisible by Sum_{i=1..k} d(i), where phi(i) is the Euler totient function of i (A000010), and d(i) is the number of divisors of i (A000005).

Table of values

n a(n)
1 1
2 5
3 19
4 21
5 154
6 604

List of values

[1, 5, 19, 21, 154, 604]

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

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