A137920 Numbers k such that 24*k-1 and 24*k+1 are twin primes.

3, 8, 10, 13, 18, 25, 43, 48, 55, 62, 67, 78, 87, 88, 108, 112, 113, 125, 130, 132, 140, 147, 153, 157, 172, 178, 200, 207, 218, 220, 230, 235, 245, 265, 273, 283, 290, 297, 312, 315, 337, 343, 375, 385, 393, 405, 407, 417, 428, 465, 473, 493, 503, 510, 542

Offset: 1

Author

Zak Seidov, Feb 23 2008

Keywords

• nonn

Links

• Robert Israel, Table of n, a(n) for n = 1..10000

Crossrefs

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

Programs

Magma

[n: n in [1..600] | IsPrime(24*n+1) and IsPrime(24*n-1)] // Vincenzo Librandi, Feb 12 2018

Maple

select(t -> isprime(24*t-1) and isprime(24*t+1), [$1..1000]); # Robert Israel, Feb 11 2018

Mathematica

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 *)
Select[Range[600], PrimeQ[24 # - 1] && PrimeQ[24 # + 1] &] (* Vincenzo Librandi, Feb 12 2018 *)

PARI

isok(k) = isprime(24*k-1) && isprime(24*k+1); \\ Michel Marcus, Feb 12 2018