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A023253 Primes that remain prime through 2 iterations of the function f(x) = 5x + 4. 3
5, 17, 83, 101, 131, 251, 257, 263, 389, 419, 461, 467, 521, 587, 797, 809, 1217, 1319, 1511, 1721, 1847, 1907, 2141, 2531, 2579, 2693, 2699, 3623, 4079, 4217, 4253, 4283, 4493, 4673, 5333, 5507, 5711, 6011, 6089, 6353, 6599, 6761, 6803, 6947, 6983, 7013 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Primes p such that 5*p+4 and 25*p+24 are also primes. - Vincenzo Librandi, Aug 04 2010

LINKS

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

FORMULA

a(n) == 5 (mod 6). - John Cerkan, Sep 13 2016

MATHEMATICA

Select[Prime[Range[1000]], AllTrue[Rest[NestList[5#+4&, #, 2]], PrimeQ]&] (* The program uses the AllTrue function from Mathematica version 10 *) (* Harvey P. Dale, Oct 19 2019 *)

PROG

(MAGMA) [n: n in [0..100000] | IsPrime(n) and IsPrime(5*n+4) and IsPrime(25*n+24)] // Vincenzo Librandi, Aug 04 2010

CROSSREFS

Subsequence of A023218.

Sequence in context: A149751 A303713 A188231 * A149752 A149753 A149754

Adjacent sequences:  A023250 A023251 A023252 * A023254 A023255 A023256

KEYWORD

nonn

AUTHOR

David W. Wilson

STATUS

approved

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Last modified August 2 02:53 EDT 2021. Contains 346409 sequences. (Running on oeis4.)