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 A111157 #24 Dec 22 2024 12:20:09 %S A111157 4,7,12,35,56,66,82,118,132,141,143,144,145,152,156,173,252 %N A111157 Numbers k such that sequence A_k in this database does not contain a prime. %C A111157 That is, the complete sequence A_k, not just the terms that are shown in the entry, does not contain a prime or the negative of a prime. The only exception to this is for sequences with keyword "dead", when only the visible terms are to be considered. %C A111157 No other terms below 287. Is 287 a member? This requires proof. %C A111157 I've checked A000287 up to a(25000) and can report that I found no prime. - _Robert G. Wilson v_, Jun 23 2014 %C A111157 A search of every term of A000287 of form a(2^k-2) has yielded no primes up to a(2^24-2). It shouldn't have any odd terms outside this subsequence, and assuming that its terms' factors are otherwise random, it has a 2.15*10^-8 probability of containing any prime at all. After A000287, the next difficult sequence is A000373, which should contain infinitely many primes, but has none within its first 10000 terms. - _Matthew House_, Nov 02 2024 %H A111157 PrimeFan, <a href="http://primefan.tripod.com/EsotericIntegerSequences.html">Esoteric Integer Sequences</a> (Gives a different version.) %H A111157 PrimeFan, <a href="/A031214/a031214.pdf">Esoteric Integer Sequences</a> [Cached copy] %H A111157 <a href="/index/Se#selfies">Index entries for sequences whose definition involves A_n (or An)</a>. %Y A111157 Cf. A111198. %K A111157 nonn,more,dumb %O A111157 1,1 %A A111157 _N. J. A. Sloane_, following a suggestion of _Alonso del Arte_, Oct 21 2005 %E A111157 a(16) = 173 inserted by _Matthew House_, Nov 02 2024