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 A089570 #5 Mar 30 2012 17:29:13 %S A089570 17,3,6,2,1,21,35,43,23,34,47,10,26,4,14,15,12,40,18,54,51,5,27,9,132, %T A089570 63,166,98,78,24,30,58,105,71,75,57,70,42,11,19,38,217,285,36,77,64, %U A089570 56,259,45,93,102,60,122,66,96,103,267,255,92,91,276,152,208,204,90,138 %N A089570 a(1) = 17. For n > 1, a(n) is the least unused number such that every concatenation a(n)a(n-1)...a(2)a(1) is prime. %C A089570 Is this a rearrangement of the natural numbers? %Y A089570 Cf. A089710, A089711, A089560-A089573. %K A089570 base,nonn %O A089570 1,1 %A A089570 _Ray Chandler_, Nov 22 2003 %E A089570 Edited by _Charles R Greathouse IV_, Apr 29 2010