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%I #19 Jun 18 2021 21:57:11
%S 1,217,510,642,710,742,782,795,862,935,1177,1207,1219,2667,3937,7590,
%T 7854,8743,9481,9798,9858,10810,10934,11186,11235,11510,11594,11715,
%U 11985,12082,12243,12903,12945,13022,13462,13587,13685,13822,14223,15085
%N Numbers whose sum of divisors is a fourth power.
%D J.-M. De Koninck, Ces nombres qui nous fascinent, Entry 217, p. 62, Ellipses, Paris 2008.
%H Donovan Johnson, <a href="/A019422/b019422.txt">Table of n, a(n) for n = 1..1000</a>
%H Frits Beukers, Florian Luca and Frans Oort, <a href="http://www.jstor.org/stable/10.4169/amer.math.monthly.119.05.373">Power Values of Divisor Sums</a>, The American Mathematical Monthly, Vol. 119, No. 5 (May 2012), pp. 373-380.
%t Select[Range[16000],IntegerQ[Power[DivisorSigma[1,#], (4)^-1]]&] (* _Harvey P. Dale_, Jan 22 2012 *)
%o (PARI) c=0; for(n=1, 8240486, if(ispower(sigma(n), 4), c++; write("b019422.txt", c " " n))) /* _Donovan Johnson_, Jun 13 2013 */
%K nonn
%O 1,2
%A _David W. Wilson_
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