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 A173883 #20 Jan 22 2013 12:49:16 %S A173883 0,0,0,0,0,1,1,2,2,2,3,2,2,3,2,2,2,4,4,4,4,4,4,4,4,4,4,3,4,4,4,4,5,4, %T A173883 4,4,4,4,4,4,4,4,4,4,4,4,8,8,8,8,6,5,4,4,4,4,4,6,4,5,4,5,4,5,5,4,4,4, %U A173883 4,5,6,5,4,6,4,4,4,4,4,4,4,8,8,8,8,8,8,8 %N A173883 a(n) = number of iterations in the sequence of classes of prime numbers for prime(n). %D A173883 Alexander S. Karpenko, Lukasiewicz's Logics and Prime Numbers, Luniver Press, Beckington, 2006, pp. 98-102. %Y A173883 Cf. A058340, A096827, A175177, A175178, A175179. %K A173883 nonn %O A173883 2,8 %A A173883 _Artur Jasinski_, Mar 01 2010 %E A173883 Edited, corrected and extended by _Arkadiusz Wesolowski_, Jan 19 2013