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Numbers k such that k | sigma_11(k).
2

%I #36 Feb 19 2024 10:28:00

%S 1,6,28,120,402,496,644,672,920,1366,1608,1932,2680,2760,3417,3966,

%T 4098,4623,4975,5152,6210,6834,8040,8128,8280,9246,9528,9950,12294,

%U 13668,15008,15456,15864,16392,18492,19900,24120,24840,25954,27320,27336,29850,30240,32760

%N Numbers k such that k | sigma_11(k).

%C sigma_11(k) is the sum of the 11th powers of the divisors of k (A013959).

%H Amiram Eldar, <a href="/A055715/b055715.txt">Table of n, a(n) for n = 1..10000</a>

%t Do[If[Mod[DivisorSigma[11, n], n]==0, Print[n]], {n, 1, 40000}]

%o (PARI) isok(k) = (sigma(k, 11) % k) == 0; \\ _Michel Marcus_, Nov 09 2019

%Y Cf. A013959.

%Y Cf. A007691, A046762, A046763, A046764, A055709, A055710, A055711, A055712, A055713, A055714.

%K nonn

%O 1,2

%A _Robert G. Wilson v_, Jun 09 2000

%E a(37)-a(40) corrected and more terms added by _Amiram Eldar_, Nov 09 2019