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.

A069084 Numbers n such that sigma(n)/tau(n) has denominator 5.

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%I A069084 #15 Sep 08 2022 08:45:05
%S A069084 16,48,80,81,112,176,208,240,272,336,368,405,496,528,560,567,592,624,
%T A069084 625,656,688,720,752,784,816,848,880,891,976,1040,1053,1072,1104,1134,
%U A069084 1136,1168,1232,1328,1360,1377,1456,1488,1536,1552,1584,1616,1620,1648
%N A069084 Numbers n such that sigma(n)/tau(n) has denominator 5.
%H A069084 Amiram Eldar, <a href="/A069084/b069084.txt">Table of n, a(n) for n = 1..10000</a>
%F A069084 n such that A057021(n)=5
%t A069084 Select[Range[500], Denominator[DivisorSigma[1, #]/DivisorSigma[0, #]] == 5 &] (* _Amiram Eldar_, Sep 08 2019 *)
%o A069084 (Magma) [n:n in [1..1700]|Denominator(SumOfDivisors(n)/#Divisors(n)) eq 5]; // _Marius A. Burtea_, Sep 08 2019
%Y A069084 Cf. A000005, A000203, A057021.
%K A069084 easy,nonn
%O A069084 1,1
%A A069084 _Benoit Cloitre_, Apr 05 2002