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 A128682 #13 Jun 08 2021 02:22:43 %S A128682 1,5,505,5905,596405,1971005,199071505,515151005,581457505,618181105, %T A128682 2327756905,11855474405,19555113485,31361954905,101901244565, %U A128682 235103447405,305354088005,395331063745,600905819065,608393336905,686701313405,730071885005 %N A128682 Numbers k such that k^3 divides 9^(k^2) + 1. %C A128682 5 divides a(n) for n > 1. %t A128682 Select[Range[5*10^6], Mod[ 9^(#^2)+1, #^3]==0 &] (* _G. C. Greubel_, Jan 18 2018 *) %Y A128682 Cf. A127263, A128677, A128678, A128679, A128680, A128681, A128683, A128684, A128685. %K A128682 nonn %O A128682 1,2 %A A128682 _Alexander Adamchuk_, Mar 31 2007 %E A128682 a(5)-a(6) from J. Mulder (jasper.mulder(AT)planet.nl), Jan 26 2010 %E A128682 Terms a(7) onward from _Max Alekseyev_, May 14 2010