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Numbers of the form 3k-1 with greatest prime divisor of the form 3m+1
3

%I #10 Jul 29 2019 20:26:59

%S 14,26,35,38,56,62,65,74,86,95,98,104,122,134,140,143,146,152,155,158,

%T 182,185,194,206,209,215,218,224,245,248,254,260,266,278,296,302,305,

%U 314,323,326,335,338,341,344,350,362,365,380,386,392,395,398,407,416,422,434,446

%N Numbers of the form 3k-1 with greatest prime divisor of the form 3m+1

%C All numbers of the form 2p, where p==1(mod 3) is prime, are in the sequence.

%H Harvey P. Dale, <a href="/A176274/b176274.txt">Table of n, a(n) for n = 1..1000</a>

%t Select[Range[500],Divisible[#+1,3]&&Divisible[FactorInteger[#] [[-1,1]]-1, 3]&] (* _Harvey P. Dale_, Jul 29 2019 *)

%o (PARI) isok(n) = ((n % 3) == 2) && ((vecmax(factor(n)[,1]) % 3) == 1); \\ _Michel Marcus_, Feb 08 2016

%Y Cf. A176262, A176258, A176257, A176256, A176255, A002148, A002145, A016813, A004767.

%K nonn

%O 1,1

%A _Vladimir Shevelev_, Apr 14 2010

%E More terms from _Michel Marcus_, Feb 08 2016