A057243 - OEIS

%I #17 Aug 09 2021 20:10:00

%S 1,2,6,13,58,169,2197,4069,4303,28561,52897,89078,122681,145457,

%T 234526,371293,442074,687661,1273597,1558427,1664221,2684903,3080233,

%U 4826809,6589141,7104253,8939593,10178701,14273909,16556761,28194101,34903739,45643351,47154211,62748517,99341411,116214709

%N Numbers k that divide 8^k + 7^k + 6^k + 5^k.

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

%o (PARI) for(n=1,10^10,if(sum(k=5,8,Mod(k,n)^n)==0,print1(n,", "))) \\ _Joerg Arndt_, Feb 23 2017

%K nonn

%O 1,2

%A _Robert G. Wilson v_, Sep 20 2000

%E More terms from _Vincenzo Librandi_ and _Joerg Arndt_, Feb 23 2017