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.

A046686 Numbers k such that k and sum of cubes of divisors of k are relatively prime.

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%I A046686 #12 Jul 23 2020 03:26:20
%S A046686 1,2,3,4,5,7,8,9,11,13,16,17,19,23,25,27,29,31,32,36,37,39,41,43,47,
%T A046686 49,50,53,55,57,59,61,63,64,65,67,71,73,75,77,79,81,83,85,89,93,97,98,
%U A046686 100,101,103,107,109,111,113,115,117,121,125,127,128,129,131,137,139,143
%N A046686 Numbers k such that k and sum of cubes of divisors of k are relatively prime.
%C A046686 All even terms are either squares or doubled squares. - _Ivan Neretin_, Dec 30 2015
%C A046686 The asymptotic density of this sequence is 0 (Dressler, 1974). - _Amiram Eldar_, Jul 23 2020
%H A046686 Ivan Neretin, <a href="/A046686/b046686.txt">Table of n, a(n) for n = 1..10000</a>
%H A046686 Robert E. Dressler, <a href="https://doi.org/10.4153/CMB-1974-019-5">On a theorem of Niven</a>, Canadian Mathematical Bulletin, Vol. 17, No. 1 (1974), pp. 109-110.
%t A046686 Select[Range[143], GCD[#, DivisorSigma[3, #]] == 1 &] (* _Ivan Neretin_, Dec 30 2015 *)
%Y A046686 Cf. A001158, A046684, A046687.
%K A046686 nonn
%O A046686 1,2
%A A046686 _Labos Elemer_