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A019424 Numbers n such that sum of divisors of n is a sixth power. 6
1, 2667, 3937, 17490, 19410, 22578, 24610, 24910, 25466, 25910, 26554, 26818, 27285, 29342, 29733, 29762, 31102, 31535, 32043, 32997, 33985, 35585, 36635, 37985, 39697, 41393, 41837, 42347, 44047, 45637, 45739, 45937, 46117, 172011, 253921, 640737 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

LINKS

Marius A. Burtea, Table of n, a(n) for n = 1..2010 (terms 1..1000 from Donovan Johnson)

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.

EXAMPLE

sigma(2667) = 1+3+7+21+127+381+889+2667 = 4096 = 4^6.

sigma(3937) = 1+31+127+3937 = 4096 = 4^6.

MATHEMATICA

Select[Range[700000], IntegerQ[Surd[DivisorSigma[1, #], 6]]&] (* Harvey P. Dale, Apr 19 2019 *)

PROG

(PARI) c=0; for(n=1, 306455560, if(ispower(sigma(n), 6), c++; write("b019424.txt", c " " n))) /* Donovan Johnson, Jun 13 2013 */

(MAGMA) [n:n in [1..100000]| IsPower(SumOfDivisors(n), 6)]; // Marius A. Burtea, Apr 17 2019

CROSSREFS

Cf. A000203, A006532, A019422, A019423, A020477, A048257, A048258.

Sequence in context: A187195 A107532 A110838 * A151813 A010088 A252301

Adjacent sequences:  A019421 A019422 A019423 * A019425 A019426 A019427

KEYWORD

nonn

AUTHOR

David W. Wilson

STATUS

approved

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Last modified October 21 13:57 EDT 2019. Contains 328299 sequences. (Running on oeis4.)