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 A217560 #20 Dec 23 2024 14:53:43 %S A217560 1,2,4,3,6,5,8,7,9,29,20,31,21,59,24,71,26,79,28,263,12,13,15,17,42, %T A217560 43,45,47,62,67,63,83,65,97,82,131,30,283,85,139,34,293,87,151,36,307, %U A217560 92,179,38,313,93,421,39,317,95,431,50,347,120,367,121,383,124,397,126,503,128,547,129,563,130,587,134,593,136,743,138,787 %N A217560 Terms as well as digits have alternating primality; this is the lexicographically earliest injective sequence with this property. %C A217560 Exactly every other term, and also every other digit (in concatenated terms) is prime. %H A217560 Carole Dubois, <a href="/A217560/b217560.txt">Table of n, a(n) for n = 1..5292</a> %H A217560 E. Angelini, <a href="https://web.archive.org/web/*/http://list.seqfan.eu/oldermail/seqfan/2012-October/010253.html">Non-primes/primes: integers and digits alternate</a>, SeqFan mailing list, Oct 06 2012 %H A217560 Carole Dubois, <a href="/A217560/a217560.jpg">Graph with even ranges and odd ranges separated</a> %Y A217560 The sequence A217559 is a simplified variant. %Y A217560 See also A217555, A217556, where "primality" is replaced by "parity". %K A217560 nonn,base %O A217560 1,2 %A A217560 _Eric Angelini_ and _M. F. Hasler_, Oct 06 2012 %E A217560 Values from a(26)=43 on corrected by _Jean-Marc Falcoz_, Oct 10 2012