%I A081424
%S A081424 283,359,557,659,941,1109,1129,1223,1433,1663,1669,1693,1787,1997,2027,
%T A081424 2039,2069,2083,2153,2339,2351,2503,2539,2579,2633,2767,2777,2803,2837,
%U A081424 2999,3229,3581,3761,3767,3779,3989,4127,4157,4231,4253,4283,4297,4513
%N A081424 Class 5- primes.
%D A081424 R. K. Guy, Unsolved Problems in Number Theory, A18.
%H A081424 R. J. Mathar, <a href="b081424.txt">Table of n, a(n) for n = 1..20000</
               a>
%t A081424 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[700], ClassMinusNbr[ Prime[ # ]] == 5 &]]
%Y A081424 Cf. A005113, A056637, A005109, A005110, A005111, A005112, A081425, A081426, 
               A081427, A081428, A081429, A081430.
%Y A081424 Sequence in context: A161191 A108836 A142937 this_sequence A142699 A113157 
               A142446
%Y A081424 Adjacent sequences: A081421 A081422 A081423 this_sequence A081425 A081426 
               A081427
%K A081424 nonn
%O A081424 1,1
%A A081424 Robert G. Wilson v (rgwv(AT)rgwv.com), Mar 20 2003