A023284 Primes that remain prime through 3 iterations of function f(x) = 5x + 4.

83, 263, 1217, 1319, 1511, 1721, 1847, 1907, 2141, 2531, 4283, 4673, 5333, 6089, 6353, 6983, 7013, 7151, 7529, 8543, 10709, 10973, 11423, 15077, 15137, 17387, 17573, 20129, 20201, 20411, 20663, 21521, 23369, 23561, 25343, 26669, 27143, 27647, 28697

Offset: 1

Author

David W. Wilson

Keywords

• nonn

Comments

Primes p such that 5*p+4, 25*p+24 and 125*p+124 are also primes. - Vincenzo Librandi, Aug 04 2010

Links

• Harvey P. Dale, Table of n, a(n) for n = 1..1000

Programs

Magma

[n: n in [1..150000] | IsPrime(n) and IsPrime(5*n+4) and IsPrime(25*n+24) and IsPrime(125*n+124)] // Vincenzo Librandi, Aug 04 2010

Mathematica

Select[Prime[Range[3500]],And@@PrimeQ[Rest[NestList[5#+4&,#,3]]]&] (* Harvey P. Dale, Feb 01 2013 *)