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 A081427 #6 Mar 30 2012 17:30:54
%S A081427 2879,20147,25903,34537,46049,58733,63317,65267,69029,69073,74759,
%T A081427 80537,86291,86341,103549,106487,108413,112877,120877,131687,135859,
%U A081427 138053,140939,141023,147647,155413,157427,165527,172681,187163,189949,207079
%N A081427 Class 8- primes.
%D A081427 R. K. Guy, Unsolved Problems in Number Theory, A18.
%H A081427 R. J. Mathar, <a href="/A081427/b081427.txt">Table of n, a(n) for n = 1..20000</a>
%t A081427 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[20000], ClassMinusNbr[ Prime[ # ]] == 8 &]]
%Y A081427 Cf. A005113, A056637, A005109, A005110, A005111, A005112, A081424, A081425, A081426, A081428, A081429, A081430.
%K A081427 nonn
%O A081427 1,1
%A A081427 _Robert G. Wilson v_, Mar 20 2003