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 A019422 Numbers n such that sum of divisors of n is a fourth power. 13
 1, 217, 510, 642, 710, 742, 782, 795, 862, 935, 1177, 1207, 1219, 2667, 3937, 7590, 7854, 8743, 9481, 9798, 9858, 10810, 10934, 11186, 11235, 11510, 11594, 11715, 11985, 12082, 12243, 12903, 12945, 13022, 13462, 13587, 13685, 13822, 14223, 15085 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 REFERENCES J.-M. De Koninck, Ces nombres qui nous fascinent, Entry 217, p. 62, Ellipses, Paris 2008. LINKS Donovan Johnson, Table of n, a(n) for n = 1..1000 Frits Beukers, Florian Luca and Frans Oort, Power Values of Divisor Sums, The American Mathematical Monthly, Vol. 119, No. 5 (May 2012), pp. 373-380. MATHEMATICA Select[Range[16000], IntegerQ[Power[DivisorSigma[1, #], (4)^-1]]&] (* Harvey P. Dale, Jan 22 2012 *) PROG (PARI) c=0; for(n=1, 8240486, if(ispower(sigma(n), 4), c++; write("b019422.txt", c " " n))) /* Donovan Johnson, Jun 13 2013 */ CROSSREFS Sequence in context: A145732 A038594 A020232 * A231558 A101826 A262052 Adjacent sequences:  A019419 A019420 A019421 * A019423 A019424 A019425 KEYWORD nonn AUTHOR STATUS approved

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Last modified October 16 15:51 EDT 2019. Contains 328101 sequences. (Running on oeis4.)