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%I #38 Mar 05 2022 00:23:08
%S 1,39,793,2379,7137,13167,76921,78507,230763,238887,549549,692289,
%T 863577,1491633,1672209,2076867,4317885,7615179,8329831,10441431,
%U 23402223,24989493,37776123,53306253,53695813,55871145,74968479,83766969,133854435,144688401,161087439,189437391
%N Numbers k that divide sigma(k^2) where sigma is the sum of divisors function (A000203).
%C Squarefree terms are: 1, 39, 793, 2379, 76921, 230763, 8329831, 24989493, 53695813, 161087439, ... Quotients are: 1, 61, 873, 3783, 11737, 26543, 85563, 141911, 370773, 417263, 1155561, ... - _Michel Marcus_, Nov 23 2013
%C Many terms are also in sequence A069520, cf. A232067 for the intersection of these two sequences. - _M. F. Hasler_, Nov 24 2013
%H Donovan Johnson, <a href="/A232354/b232354.txt">Table of n, a(n) for n = 1..200</a>
%H Jose Arnaldo Bebita Dris, <a href="https://arxiv.org/abs/2202.08116">A new approach to odd perfect numbers via GCDs</a>, arXiv:2202.08116 [math.NT], 2022.
%F A065764(a(n)) mod a(n) = 0.
%t Select[Range[10^5], Divisible[DivisorSigma[1, #^2], #] &] (* _Alonso del Arte_, Dec 06 2013 *)
%o (PARI) isok(n) = (sigma(n^2) % n) == 0; \\ _Michel Marcus_, Nov 23 2013
%Y Cf. A000203, A007691, A065764, A069520, A227302, A232067, A232703, A232704.
%K nonn
%O 1,2
%A _Alex Ratushnyak_, Nov 22 2013
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