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 A050259 #46 Feb 16 2025 08:32:40 %S A050259 1,4700063497,3468371109448915,8365386194032363,10991007971508067 %N A050259 Numbers n such that 2^n == 3 (mod n). %C A050259 No other terms below 10^18. - _Max Alekseyev_, Oct 17 2017 %C A050259 Terms were computed: a(2) by the Lehmers, a(3) by _Max Alekseyev_, a(4) and a(5) by Joe K. Crump, a(?) = 63130707451134435989380140059866138830623361447484274774099906755 by P.-L. Montgomery. %D A050259 R. Daniel Mauldin and S. M. Ulam, Mathematical problems and games. Adv. in Appl. Math. 8 (1987), pp. 281-344. %H A050259 Joe K. Crump, <a href="http://web.archive.org/web/20120104074313/http://www.immortaltheory.com/NumberTheory/2nmodn.htm">2^n mod n</a> %H A050259 R. K. Guy, <a href="https://www.maa.org/sites/default/files/pdf/upload_library/22/Ford/Guy697-712.pdf">The Strong Law of Small Numbers</a>, Amer. Math. Monthly 95 (1988), pp. 697-712. See example 13. %H A050259 R. K. Guy, <a href="/A005165/a005165.pdf">The strong law of small numbers</a>. Amer. Math. Monthly 95 (1988), no. 8, 697-712. [Annotated scanned copy] %H A050259 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/2.html">2</a> %H A050259 OEIS Wiki, <a href="/wiki/2^n mod n">2^n mod n</a> %t A050259 m = 2; Join[Select[Range[m], Divisible[2^# - m, #] &], %t A050259 Select[Range[m + 1, 10^6], PowerMod[2, #, #] == m &]] (* _Robert Price_, Oct 08 2018 *) %o A050259 (PARI) is(n)=Mod(2,n)^n==3 \\ _Charles R Greathouse IV_, Jun 11 2015 %Y A050259 Cf. A001567, A036236, A015940, A015910. %K A050259 nonn,more,hard %O A050259 1,2 %A A050259 _Eric W. Weisstein_