A274381 Safe primes p such that p + 24 is also a safe prime.

23, 59, 83, 359, 479, 563, 839, 863, 1283, 2039, 2879, 2999, 3779, 4259, 4679, 5483, 7703, 10079, 12203, 13103, 23603, 26903, 27803, 30323, 31583, 33623, 35339, 41519, 43403, 44519, 44939, 53759, 55079, 57119, 57899, 58043, 65123, 66359, 70139, 70199, 76379, 77723, 79943

Offset

1,1

Links

John Cerkan, Table of n, a(n) for n = 1..10000

Formula

{ x | both x and x + 24 are safe primes }.

Example

83 is a safe prime and so is 83 + 24 = 107.
4679 is a safe prime and so is 4679 + 24 = 4703.

Maple

A274381:=n->`if`(type((n-1)/2, prime) and isprime(n+24) and isprime(n) and type((n+23)/2, prime), n, NULL): seq(A274381(n), n=1..10^5); # Wesley Ivan Hurt, Jun 25 2016

Mathematica

Select[Prime@ Range[10^4], PrimeQ[(# - 1)/2] && PrimeQ[# + 24] && PrimeQ[(23 + #)/2] &] (* Giovanni Resta, Jun 23 2016 *)
Select[Prime[Range[8000]], AllTrue[{(#-1)/2, (#+23)/2, #+24}, PrimeQ]&] (* The program uses the AllTrue function from Mathematica version 10 *) (* Harvey P. Dale, Dec 31 2019 *)

Prog

(PARI) lista(nn) = forprime(p=3, nn, if (isprime((p-1)/2) && isprime(q=p+24) && isprime((q-1)/2), print1(p, ", "))); \\ Michel Marcus, Jun 23 2016

Crossrefs

Cf. A005385, A033560, A059323.

Sequence in context: A005111 A225550 A179629 * A044125 A044506 A033217

Adjacent sequences: A274378 A274379 A274380 * A274382 A274383 A274384

Keyword

nonn

Author

Debapriyay Mukhopadhyay, Jun 23 2016

Status

approved