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Numbers n such that n | 9^n + 8^n + 7^n + 6^n.
1

%I #6 Feb 06 2019 11:19:15

%S 1,2,3,5,9,10,15,25,27,45,46,50,75,81,99,125,135,225,243,250,375,405,

%T 485,625,675,729,1125,1215,1250,1875,2025,2187,2650,3125,3375,3645,

%U 4401,4975,5050,5625,6075,6250,6561,8019,9375,10125,10341,10935,11325

%N Numbers n such that n | 9^n + 8^n + 7^n + 6^n.

%H Harvey P. Dale, <a href="/A057242/b057242.txt">Table of n, a(n) for n = 1..250</a>

%t Select[ Range[ 1, 10^5 ], Mod[ PowerMod[ 9, #, # ] + PowerMod[ 8, #, # ] + PowerMod[ 7, #, # ] + PowerMod[ 6, #, # ], # ] == 0 & ]

%t Select[Range[12000], Mod[Total[PowerMod[Range[6, 9], #, #]], #] == 0 &] (* _Harvey P. Dale_, Feb 06 2019 *)

%K nonn

%O 1,2

%A _Robert G. Wilson v_, Sep 20 2000