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 A248919 #33 Dec 23 2024 14:53:44 %S A248919 13,131,653,883,1279,10739,17669 %N A248919 "Stubborn primes" (see comments in A232210). %C A248919 Terms a(2)-a(5) were obtained by _Peter J. C. Moses_. %C A248919 Terms a(6)-a(7) were obtained by _Hans Havermann_ (cf. b-file in A232210). %C A248919 Hypothetically, a(8) = 26293 = A232210(2889). %C A248919 However, there are two conjectures: 1) for every n, prime a(n) exists (Shevelev); 2) already prime a(8) does not exist (Havermann). %C A248919 _M. F. Hasler_ showed that, if a prime of the form 262933...3 > 26293 exists, then it has at least several thousand digits. %C A248919 Note that, for a(n), n=1,...,7, the number of digits of the smallest prime of the form a(n)*10^k+3...3 (k 3's) respectively equals 16, 26, 53, 255, 4756, 6525, 9677. Judging from the ratio 4756/255 > 18.65, the smallest prime of the form 262933...3 could have more than 180000 digits. %H A248919 Vladimir Shevelev, <a href="https://web.archive.org/web/*/http://list.seqfan.eu/oldermail/seqfan/2014-September/013620.html">"Stubborn primes"</a> %Y A248919 Cf. A000040, A232210. %K A248919 nonn,base,more %O A248919 1,1 %A A248919 _Vladimir Shevelev_, Oct 16 2014