The OEIS is supported by the many generous donors to the OEIS Foundation.
Reminder: The OEIS is hiring a new managing editor, and the application deadline is January 26.
Reminder: The OEIS is hiring a new managing editor, and the application deadline is January 26.
%I #7 Jan 13 2014 12:00:30
%S 15013,16333,22093,24841,43321,49003,52517,54721,62533,63761,69061,
%T 69073,70061,74597,75781,75793,75913,82561,83233,84673,87433,87509,
%U 88793,91081,92761,94321,98737,99367,101641,105097,110881,111973,114343
%N Class 7+ primes.
%D R. K. Guy, Unsolved Problems in Number Theory, A18.
%H T. D. Noe, <a href="/A081635/b081635.txt">Table of n, a(n) for n=1..10000</a>
%p For Maple program see Mathar link in A005105.
%t 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[10820], ClassPlusNbr[ Prime[ # ]] == 7 &]]
%Y Cf. A005113, A005105, A005106, A005107, A005108, A081633, A081634, A081636, A081637, A081638, A081639.
%K nonn
%O 1,1
%A _Robert G. Wilson v_, Mar 20 2003