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 A245728 #35 Aug 16 2021 03:21:00 %S A245728 1,2,10,1030,10009593662,13957196317,55299492770,3764656723270 %N A245728 Numbers k that divide 2^k + 6. %C A245728 No other terms below 10^15. Some larger terms: 2962089521722084981, 1376243703434217460265762. - _Max Alekseyev_, Sep 23 2016 %H A245728 OEIS Wiki, <a href="/wiki/2^n mod n">2^n mod n</a> %e A245728 2^10 + 6 = 1030 is divisible by 10. Thus 10 is a term of this sequence. %p A245728 select(n -> 2 &^ n + 6 mod n = 0, [$1..10^6]); # _Robert Israel_, Jul 30 2014 %t A245728 Select[Range[10^5], Divisible[2^# + 6, #] &] (* _Robert Price_, Oct 12 2018 *) %o A245728 (PARI) %o A245728 for(n=1,10^9,if(Mod(2,n)^n==Mod(-6,n),print1(n,", "))) %Y A245728 Cf. A015910, A128122, A153972. %K A245728 nonn,more,hard %O A245728 1,2 %A A245728 _Derek Orr_, Jul 30 2014 %E A245728 a(5) from _Jason G. Wurtzel_, Sep 25 2014 %E A245728 a(6)-a(8) from _Max Alekseyev_, Sep 23 2016