%I A005106 M4889
%S A005106 13,19,29,41,43,59,61,67,79,83,89,97,101,109,131,137,139,149,167,179,
%T A005106 197,199,211,223,229,239,241,251,263,269,271,281,283,293,307,317,349,
%U A005106 359,367,373,419,433,439,449,461,479,499,503,509,557,563,577,587,593
%N A005106 Class 2+ primes.
%D A005106 N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, 
               Academic Press, 1995 (includes this sequence).
%D A005106 R. K. Guy, Unsolved Problems in Number Theory, A18.
%p A005106 For Maple program see Mathar link.
%t A005106 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[120], ClassPlusNbr[ Prime[ # ]] == 2 &]]
%Y A005106 Cf. A005113, A005105, A005107, A005108.
%Y A005106 Sequence in context: A073620 A089391 A038954 this_sequence A050265 A120140 
               A101849
%Y A005106 Adjacent sequences: A005103 A005104 A005105 this_sequence A005107 A005108 
               A005109
%K A005106 nonn
%O A005106 1,1
%A A005106 N. J. A. Sloane (njas(AT)research.att.com), Simon Plouffe (simon.plouffe(AT)gmail.com)
%E A005106 Edited and extended by Robert G. Wilson v (rgwv(AT)rgwv.com), Mar 20 
               2003