A253939 - OEIS

%I #14 Sep 08 2022 08:46:11

%S 7309,45361,67103,97777,128521,149381,374669,543313,656459,872747,

%T 940913,1110817,1219877,1288603,1324567,1599319,1629809,2006677,

%U 2129527,2495501,2544121,2735839,2763053,2786363,2856167,3145661,3428839,3585149,4063877,4115971

%N Primes p such that (p^2 + 5)/6, (p^4 + 5)/6 and (p^6 + 5)/6 are prime.

%H R. J. Mathar, <a href="/A253939/b253939.txt">Table of n, a(n) for n = 1..125</a>

%t Select[Prime[Range[10^7]], PrimeQ[(#^2 + 5) / 6] &&PrimeQ[(#^4 + 5) / 6] &&PrimeQ[(#^6 + 5) / 6] &] (* _Vincenzo Librandi_, Jan 21 2015 *)

%t Select[Prime[Range[3*10^5]],AllTrue[(#^{2,4,6}+5)/6,PrimeQ]&] (* The program uses the AllTrue function from Mathematica version 10 *) (* _Harvey P. Dale_, Mar 10 2016 *)

%o (Magma) [p: p in PrimesUpTo(10^7) | IsPrime((p^2+5) div 6) and IsPrime((p^4+5) div 6) and IsPrime((p^6+5) div 6)]; // _Vincenzo Librandi_, Jan 21 2015

%Y Subsequence of A253925. Cf. A118915, A247478.

%K nonn

%O 1,1

%A _Zak Seidov_, Jan 20 2015