A123986 - OEIS

%I #22 Sep 08 2022 08:45:28

%S 1,4,7,10,25,34,37,49,67,70,115,130,142,154,160,202,205,214,220,262,

%T 265,307,319,322,325,370,424,430,469,487,499,520,532,535,559,577,595,

%U 637,664,682,697,700,742,814,832,847,865,889,895,955,979,982,1000,1012,1039

%N Numbers n for which 4n+1 and 4n+3 are primes.

%C All terms == 1 mod 3. - _Zak Seidov_, Dec 02 2011

%C Intersection of A005098 and A095278. - _Michel Marcus_, Jan 31 2015

%H Zak Seidov, <a href="/A123986/b123986.txt">Table of n, a(n) for n = 1..10000</a>

%t Select[Range[1100], And @@ PrimeQ /@ ({1, 3} + 4#) &] (* _Ray Chandler_, Nov 05 2006 *)

%t nn=10000;k=0;x=1;re=Reap[While[k<nn-.1,If[PrimeQ[1+4x]&&PrimeQ[3+4x],Sow[x];k++];x=x+3]][[2,1]] (* _Zak Seidov_, Dec 02 2011 *)

%o (Magma) [n: n in [0..1100] |IsPrime(4*n+1) and IsPrime(4*n+3)]; // _Vincenzo Librandi_, Feb 01 2015

%Y Cf. A005098, A005099, A095278.

%K nonn

%O 1,2

%A _Artur Jasinski_, Oct 30 2006

%E Extended by _Ray Chandler_, Nov 05 2006