Search: id:A005108 Results 1-1 of 1 results found. %I A005108 M5350 %S A005108 73,313,443,617,661,673,677,691,739,757,823,887,907,941,977,1093,1109, %T A005108 1129,1201,1213,1303,1361,1447,1453,1543,1553,1621,1627,1657,1753,1811, %U A005108 1867,1873,1993,1997,2017,2081,2083,2113,2269,2273,2281,2293,2333,2341 %N A005108 Class 4+ primes. %D A005108 R. K. Guy, Unsolved Problems in Number Theory, A18. %D A005108 N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence). %p A005108 For Maple program see Mathar link. %t A005108 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[350], ClassPlusNbr[ Prime[ # ]] == 4 &]] %Y A005108 Cf. A005113, A005105, A005106, A005107. %Y A005108 Sequence in context: A142614 A158744 A142406 this_sequence A142810 A142279 A092342 %Y A005108 Adjacent sequences: A005105 A005106 A005107 this_sequence A005109 A005110 A005111 %K A005108 nonn %O A005108 1,1 %A A005108 N. J. A. Sloane (njas(AT)research.att.com), Simon Plouffe (simon.plouffe(AT)gmail.com) %E A005108 Edited and extended by Robert G. Wilson v (rgwv(AT)rgwv.com), Mar 20 2003 Search completed in 0.002 seconds