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 A090468 #10 Jan 13 2014 12:14:30
%S A090468 545587687,852480757,1048438561,1150849009,1323457987,1745980517,
%T A090468 1756123441,1785398401,1798736161,1892507347,1937020021,2002155601,
%U A090468 2136716521,2150905573,2229004913,2548101601,2671514917,2838761021
%N A090468 Class 13+ primes.
%D A090468 R. K. Guy, Unsolved Problems in Number Theory, A18.
%H A090468 M. F. Hasler, <a href="/A090468/b090468.txt">Table of n, a(n) for n=1..850</a>
%p A090468 For Maple program see Mathar link in A005105.
%t A090468 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]]; ClassPlusNbr[n_] := Length[ NestWhileList[f, n, UnsameQ, All]] - 3; Prime[ Select[ Range[195000000], ClassPlusNbr[ Prime[ # ]] == 13 &]]
%Y A090468 Cf. A005113, A005105 - A005108, A081633 - A081639, A084071, A129474.
%K A090468 nonn
%O A090468 1,1
%A A090468 _Robert G. Wilson v_, Nov 26 2003