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 A089562 #6 Mar 30 2012 17:29:13 %S A089562 7,1,3,6,2,21,10,9,8,37,20,25,29,72,28,30,27,23,39,19,51,32,22,54,42, %T A089562 35,24,73,36,120,44,186,4,26,126,171,70,33,18,60,113,99,81,76,47,108, %U A089562 91,170,159,49,65,114,238,185,285,34,98,312,63,183,15,205,230,198,310,524 %N A089562 a(1) = 7. 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 A089562 Is this a rearrangement of the natural numbers? %Y A089562 Cf. A089710, A089711, A089560-A089573. %K A089562 base,nonn %O A089562 1,1 %A A089562 _Ray Chandler_, Nov 22 2003 %E A089562 Edited by _Charles R Greathouse IV_, Apr 29 2010