A137920 - OEIS

%I #18 Sep 08 2022 08:45:33

%S 3,8,10,13,18,25,43,48,55,62,67,78,87,88,108,112,113,125,130,132,140,

%T 147,153,157,172,178,200,207,218,220,230,235,245,265,273,283,290,297,

%U 312,315,337,343,375,385,393,405,407,417,428,465,473,493,503,510,542

%N Numbers k such that 24*k-1 and 24*k+1 are twin primes.

%H Robert Israel, <a href="/A137920/b137920.txt">Table of n, a(n) for n = 1..10000</a>

%p select(t -> isprime(24*t-1) and isprime(24*t+1), [$1..1000]); # _Robert Israel_, Feb 11 2018

%t q=24; lst={}; Do[r=n*q; If[PrimeQ[r-1]&&PrimeQ[r+1], AppendTo[lst, n]], {n, 1, 10^3}]; lst (* _Vladimir Joseph Stephan Orlovsky_, Aug 07 2008 *)

%t Select[Range[600], PrimeQ[24 # - 1] && PrimeQ[24 # + 1] &] (* _Vincenzo Librandi_, Feb 12 2018 *)

%o (PARI) isok(k) = isprime(24*k-1) && isprime(24*k+1); \\ _Michel Marcus_, Feb 12 2018

%o (Magma) [n: n in [1..600] | IsPrime(24*n+1) and IsPrime(24*n-1)] // _Vincenzo Librandi_, Feb 12 2018

%Y Cf. A124519, A135023, A135368, A137876, A137877, A137919.

%K nonn

%O 1,1

%A _Zak Seidov_, Feb 23 2008