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 A056741 #15 Jun 26 2025 12:08:39
%S A056741 1,3,5,9,15,25,27,45,75,81,125,135,225,243,261,295,375,405,625,675,
%T A056741 729,925,1125,1215,1875,2025,2187,3125,3375,3645,4077,4833,5139,5625,
%U A056741 6075,6345,6561,9375,10125,10935,15625,16875,17895,18125,18225,18495,19683
%N A056741 Numbers k such that k | 5^k + 4^k + 3^k + 2^k + 1^k.
%C A056741 All terms are odd. The only primes in the sequence are 3 and 5. - _Robert Israel_, Jun 25 2025
%H A056741 Robert Israel, <a href="/A056741/b056741.txt">Table of n, a(n) for n = 1..300</a> (first 100 terms from Harvey P. Dale)
%p A056741 filter:= n -> 5&^n + 4&^n + 3&^n + 2&^n + 1 mod n = 0:
%p A056741 select(filter, [seq(i,i=1..10^5,2)]); # Robert Israel, Jun 25 2025
%t A056741 Do[ If[ Mod[ PowerMod[ 5, n, n ] + PowerMod[ 4, n, n ] + PowerMod[ 3, n, n ] + PowerMod[ 2, n, n ] + 1, n ] == 0, Print[ n ] ], {n, 1, 10^6} ]
%t A056741 Select[Range[20000],Mod[Total[PowerMod[Range[0,5],#,#]],#]==0&] (* _Harvey P. Dale_, Oct 09 2021 *)
%Y A056741 Cf. A001552, A056739, A057291, A057292.
%K A056741 nonn
%O A056741 1,2
%A A056741 _Robert G. Wilson v_, Aug 25 2000