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Numbers k such that 5*k + 1 is prime.
9

%I #30 Dec 15 2023 20:29:03

%S 2,6,8,12,14,20,26,30,36,38,42,48,50,54,56,62,66,80,84,86,92,98,104,

%T 108,114,120,126,128,132,138,140,150,152,162,164,176,182,188,194,198,

%U 204,206,210,212,218,230,234,236,240,246,258,260,264,272,276,290,294,296,302,306,314

%N Numbers k such that 5*k + 1 is prime.

%C a(n) = (A030430(n) - 1) / 5. - _Reinhard Zumkeller_, Aug 15 2013

%H Charles R Greathouse IV, <a href="/A024894/b024894.txt">Table of n, a(n) for n = 1..10000</a>

%F a(n) ~ 0.8n log n. - _Charles R Greathouse IV_, Apr 16 2012

%t Select[Range[350], PrimeQ[5 # + 1] &] (* _Vincenzo Librandi_, May 20 2014 *)

%o (Magma) [n: n in [0..1000] | IsPrime(5*n+1)]; // _Vincenzo Librandi_, Nov 20 2010

%o (PARI) is(n)=isprime(5*n+1) \\ _Charles R Greathouse IV_, Apr 16 2012

%o (Haskell)

%o a024894 = flip div 5 . subtract 1 . a030430

%o -- _Reinhard Zumkeller_, Aug 15 2013

%Y Cf. A030430.

%K nonn,easy

%O 1,1

%A _Clark Kimberling_