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Numbers n such that n | 9^n + 7^n + 5^n + 3^n.
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%I #7 Dec 15 2017 17:35:21

%S 1,2,3,4,9,27,51,81,82,207,243,297,729,2187,2277,4131,6561,9668,10233,

%T 17457,19683,24057,27028,30699,33777,33849,50301,52351,56727,59049,

%U 92097,112102,133837,134297,136809,177147,184437,197667,256243,264357

%N Numbers n such that n | 9^n + 7^n + 5^n + 3^n.

%t Select[ Range[ 200000 ], Mod[ PowerMod[ 9, #, # ] + PowerMod[ 7, #, # ] + PowerMod[ 5, #, # ] + PowerMod[ 3, #, # ], # ] == 0 & ]

%o (PARI) j=[]; for(n=1,20000,a=9^n+7^n+5^n+3^n; if(Mod(a,n) == 0,j=concat(j,n))); j

%K nonn

%O 1,2

%A _Jason Earls_, Jul 25 2001

%E More terms from _Robert G. Wilson v_ and Dean Hickerson, Jul 26 2001