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 A089560 #5 Mar 30 2012 17:29:13 %S A089560 1,3,4,5,7,14,9,6,57,13,18,17,16,12,20,82,42,21,45,78,98,33,133,50,28, %T A089560 41,124,36,44,19,80,40,75,63,372,168,179,85,84,128,64,302,151,248,10, %U A089560 69,123,11,54,31,149,34,185,51,213,43,282,105,125,237,55,174,96,438,215,61 %N A089560 a(1) = 1. For n > 1, a(n) is the least unused number such that the concatenation a(n)a(n-1)...a(2)a(1) is prime. %C A089560 Is this a rearrangement of the natural numbers? %Y A089560 Cf. A089710, A089711, A089561-A089573. %K A089560 base,nonn %O A089560 1,2 %A A089560 _Ray Chandler_, Nov 22 2003 %E A089560 Edited by _Charles R Greathouse IV_, Apr 29 2010