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%I #5 Jul 20 2021 11:44:00
%S 1,3,5,9,15,25,27,45,75,81,87,125,135,155,225,243,265,297,375,405,625,
%T 675,729,775,1107,1125,1215,1875,2025,2187,3125,3375,3645,3875,4779,
%U 4805,5625,6075,6561,9369,9375,10125,10935,12175,12879,15625,16875
%N Numbers n such that n | 11^n + 10^n + 9^n + 8^n + 7^n.
%t Select[ Range[ 10^5 ], Mod[ PowerMod[ 11, #, # ] + PowerMod[ 10, #, # ] + PowerMod[ 9, #, # ] + PowerMod[ 8, #, # ] + PowerMod[ 7, #, # ], # ] == 0 & ]
%t Select[Range[17000],Mod[Total[PowerMod[Range[7,11],#,#]],#]==0&] (* _Harvey P. Dale_, Jul 20 2021 *)
%K nonn
%O 1,2
%A _Robert G. Wilson v_, Sep 21 2000