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 A145443 #6 Jan 29 2014 17:16:03 %S A145443 1,2,2,2,2,1,3,1,1,2,0,0,0,1,0,1,3,0,1,0,1,1,0,0,1,1,0,0,4,0,1,0,0,0, %T A145443 0,0,0,0,0,0,2,0,0,0,0,0,0,0,1,0,1,1,0,0,1,0,0,1,1,1,0,0,1,0,2,2,1,0, %U A145443 1,0,2,0,0,1,0,0,1,0,1,0,1,1,0,0,0,0,2,0,2,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0 %N A145443 In class n of the phi iteration, the number of primes less than the smallest composite number. %C A145443 A number is in class n if n iterations of Euler's phi function produces 2 (see A032358). a(n)>0 for the n in A136040. %H A145443 T. D. Noe, <a href="/A145443/b145443.txt">Table of n, a(n) for n=1..1000</a> %H A145443 T. D. Noe, <a href="http://www.sspectra.com/math/IteratedPhi2.pdf">Computing Numbers in Section I of the Totient Iteration</a> %e A145443 According to A005239, class 5 begins with 41, 47, 51, 53, 55, 59, 61. There are two primes less than the composite 51. Hence a(5)=2. %Y A145443 A098196 %K A145443 nonn %O A145443 1,2 %A A145443 _T. D. Noe_, Oct 10 2008 %E A145443 Modified comment. - _T. D. Noe_, Nov 18 2008 %E A145443 Extension _T. D. Noe_, Nov 18 2008