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 A089572 #5 Mar 30 2012 17:29:13 %S A089572 19,4,5,3,7,9,15,14,1,60,26,28,6,20,13,74,30,111,45,12,16,11,31,102, %T A089572 144,72,27,65,33,79,21,77,147,91,47,96,37,2,106,200,46,54,44,75,141, %U A089572 126,165,178,63,36,51,78,210,170,85,143,183,70,48,83,225,411,142,461,270,124 %N A089572 a(1) = 19. 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 A089572 Is this a rearrangement of the natural numbers? %Y A089572 Cf. A089710, A089711, A089560-A089573. %K A089572 base,nonn %O A089572 1,1 %A A089572 _Ray Chandler_, Nov 22 2003 %E A089572 Edited by _Charles R Greathouse IV_, Apr 29 2010