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%I #26 Feb 25 2024 05:57:58
%S 1,6,28,86,120,145,258,290,435,496,580,588,672,696,870,946,1032,1305,
%T 1720,1740,2245,2610,2712,2838,3164,3282,3408,3480,3724,3784,4060,
%U 4490,5160,5220,6735,6786,6960,7830,8514,8980,9436,9492,9632,9976
%N Numbers k such that k | sigma_7(k).
%C sigma_7(k) is the sum of the 7th powers of the divisors of k (A013955).
%C Problem 11090 proves that this sequence is infinite. - _T. D. Noe_, Apr 18 2006
%H Amiram Eldar, <a href="/A055711/b055711.txt">Table of n, a(n) for n = 1..10000</a>
%H Florian Luca and John Ferdinands, <a href="http://www.jstor.org/stable/27641939">Problem 11090: Sometimes n divides sigma_k(n)</a>, Amer. Math. Monthly 113:4 (2006), pp. 372-373.
%t Do[If[Mod[DivisorSigma[7, n], n]==0, Print[n]], {n, 1, 10000}]
%o (PARI) is(n)=sigma(n,7)%n==0 \\ _Charles R Greathouse IV_, Feb 04 2013
%Y Cf. A013955.
%Y Cf. A055709, A055710, A055712, A055713.
%K nonn
%O 1,2
%A _Robert G. Wilson v_, Jun 09 2000
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