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Numbers n such that 210*n-1 is prime.
1

%I #12 Sep 08 2022 08:45:07

%S 2,4,5,6,9,10,11,13,14,16,18,19,21,24,27,28,29,30,32,35,36,41,42,43,

%T 44,48,49,50,51,55,57,61,63,65,66,69,70,73,75,76,86,87,90,92,94,95,97,

%U 99,102,104,106,107,108,110,116,119,121,125,126,127,128,130,131,135

%N Numbers n such that 210*n-1 is prime.

%H Vincenzo Librandi, <a href="/A076354/b076354.txt">Table of n, a(n) for n = 1..1000</a>

%e n=2: 210*2-1=419 is prime.

%t Select[Range[300], PrimeQ[210*# - 1] &] (* _Vincenzo Librandi_, Oct 04 2012 *)

%o (Magma) [n: n in [0..150]| IsPrime(210*n - 1)]; // _Vincenzo Librandi_, Oct 04 2012

%o (PARI) is(n)=isprime(210*n-1) \\ _Charles R Greathouse IV_, Jun 12 2017

%K easy,nonn

%O 1,1

%A _Zak Seidov_, Oct 08 2002