A173904 - OEIS

%I #7 Sep 08 2022 08:45:50

%S 6,60,66,126,150,156,186,204,246,276,306,324,330,384,390,480,504,546,

%T 594,606,684,774,786,840,870,876,900,936,966,1044,1050,1080,1176,1260,

%U 1266,1320,1326,1434,1476,1494,1500,1530,1596,1650,1674,1710,1914,1956

%N Numbers n such that 7*n+-1 are prime.

%H Vincenzo Librandi, <a href="/A173904/b173904.txt">Table of n, a(n) for n = 1..1000</a>

%t Select[Range[2000], PrimeQ[7 # + 1]&& PrimeQ[7 # - 1]&] (* _Vincenzo Librandi_, Apr 05 2013 *)

%o (Magma) [n: n in [1..2000] | IsPrime(7*n+1) and IsPrime(7*n-1)]

%K nonn,easy

%O 1,1

%A _Vincenzo Librandi_, Mar 08 2010