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 A005111 M5133 #18 Sep 22 2012 11:09:59
%S A005111 23,59,67,83,89,107,173,199,227,233,263,311,317,331,349,353,367,373,
%T A005111 383,397,419,431,463,479,503,509,523,563,569,587,607,617,619,661,683,
%U A005111 727,733,739,743,787,809,821,823,853,859,881,887,907,929,947,977,983,991,1031,1033
%N A005111 Class 3- primes (for definition see A005109).
%D A005111 R. K. Guy, Unsolved Problems in Number Theory, A18.
%D A005111 N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
%H A005111 R. J. Mathar, <a href="/A005111/b005111.txt">Table of n, a(n) for n = 1..20000</a>
%t A005111 PrimeFactors[n_Integer] := Flatten[ Table[ #[[1]], {1}] & /@ FactorInteger[n]]; f[n_Integer] := Block[{m = n}, If[m == 0, m = 1, While[ IntegerQ[m/2], m /= 2]; While[ IntegerQ[m/3], m /= 3]]; Apply[Times, PrimeFactors[m] - 1]]; ClassMinusNbr[n_] := Length[NestWhileList[f, n, UnsameQ, All]] - 3; Prime[ Select[ Range[175], ClassMinusNbr[ Prime[ # ]] == 3 &]]
%Y A005111 Cf. A005113, A056637, A005109, A005110, A005112, A081424, A081425, A081426, A081427, A081428, A081429, A081430.
%K A005111 nonn
%O A005111 1,1
%A A005111 _N. J. A. Sloane_, _Simon Plouffe_
%E A005111 Edited and extended by _Robert G. Wilson v_, Mar 20 2003
%E A005111 Corrected by R. J. Mathar, Feb 01 2007