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%I #26 Feb 25 2024 05:58:06
%S 1,6,38,42,54,114,120,135,168,190,216,222,266,270,280,285,312,342,378,
%T 456,496,540,570,672,728,760,798,840,888,945,1026,1064,1080,1140,1330,
%U 1512,1554,1560,1710,1782,1806,1862,1890,1962,1976,1995,1998,2160,2166
%N Numbers k such that k | sigma_9(k).
%C sigma_9(k) is the sum of the 9th powers of the divisors of k (A013957).
%C Problem 11090 proves that this sequence is infinite. - _T. D. Noe_, Apr 18 2006
%H Amiram Eldar, <a href="/A055713/b055713.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[9, n], n]==0, Print[n]], {n, 1, 5000}]
%o (PARI) is(n)=sigma(n,9)%n==0 \\ _Charles R Greathouse IV_, Feb 04 2013
%Y Cf. A013957.
%Y Cf. A055709, A055710, A055711, A055712.
%K nonn
%O 1,2
%A _Robert G. Wilson v_, Jun 09 2000
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