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 A343538 #16 Apr 30 2021 17:18:29 %S A343538 13,61,63,67,19,99,31,69,91,87,79,37,39,43,27,49,73,51 %N A343538 Longest sequence of distinct two-digit numbers (10-99) such that any two or three consecutive terms can be concatenated into a prime number, even when connected into a loop. Smallest number is listed first. %C A343538 A total of 164 sequences exist from two to eighteen terms. Checked to a depth of 50 terms with two different programs. 11262 sequences with two to twenty-one terms exist if the demand on connecting the sequence into a loop is removed. %D A343538 Andreas Boe, The Toy Robot, Amazon, 2014, Afterword Quiz. %H A343538 Andreas Boe, <a href="/A343538/a343538.txt">All 2-digit looped sequences</a> %H A343538 <a href="https://nerdology.info/pics/alarmclock.jpg">Illustration for 11,17,33,47,93,71,51,53,81,23,41,39</a> %e A343538 13,61,63,67 -> 1361, 6163, 6367, 136163, 616367 are all prime numbers. %K A343538 nonn,base,fini,full %O A343538 1,1 %A A343538 _Andreas Boe_, Apr 18 2021