This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A057490 #32 Aug 09 2021 20:09:40 %S A057490 1,5,7,25,35,49,125,175,245,301,343,455,625,875,1225,1295,1435,1505, %T A057490 1715,1765,2107,2191,2401,3125,4375,6125,7525,8575,10535,11375,12005, %U A057490 12943,14063,14749,15625,16807,21875,22295,30625,35875,37625,42875,52675,60025,64715,70315,73745,78125,80375,84035,90601,93275 %N A057490 Numbers k that divide 8^k + 7^k + 6^k + 5^k + 4^k + 3^k + 2^k. %C A057490 Contains A003595. The first term not in A003595 is 301. Is 1 the only term not divisible by 5 or 7? - _Robert Israel_, Feb 22 2017 %C A057490 No term is divisible by 3. 5 and 7 are the only primes in this sequence. - _Altug Alkan_, Feb 23 2017 %p A057490 select(t -> add(i &^ t, i=2..8) mod t = 0, [$1..10^6]); # _Robert Israel_, Feb 22 2017 %t A057490 Select[ Range[ 10^5 ], Mod[ PowerMod[ 8, #, # ] + PowerMod[ 7, #, # ] + PowerMod[ 6, #, # ] + PowerMod[ 5, #, # ] + PowerMod[ 4, #, # ] + PowerMod[ 3, #, # ] + PowerMod[ 2, #, # ], # ] == 0 & ] %t A057490 Select[Range[100000],Mod[Total[PowerMod[Range[2,8],#,#]],#]==0&] (* _Harvey P. Dale_, Jul 28 2021 *) %Y A057490 Cf. A003595. %K A057490 nonn %O A057490 1,2 %A A057490 _Robert G. Wilson v_, Sep 22 2000