A023326 Primes that remain prime through 4 iterations of the function f(x) = 9x + 8.

397, 467, 907, 1747, 1901, 4099, 7237, 8117, 8581, 9371, 9587, 23539, 28081, 32611, 36899, 41729, 54767, 55207, 57601, 61991, 64997, 66449, 73061, 74821, 75527, 86291, 115021, 118717, 125659, 126067, 134287, 140677, 147011, 148147, 151531, 171539

Offset: 1

Author

David W. Wilson

Keywords

• nonn

Comments

Primes p such that 9*p+8, 81*p+80, 729*p+728 and 6561*p+6560 are also primes. - Vincenzo Librandi, Aug 04 2010

Links

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

Crossrefs

Subsequence of A023235, A023267, and A023298.

Programs

Magma

[n: n in [1..5000000] | IsPrime(n) and IsPrime(9*n+8) and IsPrime(81*n+80) and IsPrime(729*n+728) and IsPrime(6561*n+6560)] // Vincenzo Librandi, Aug 04 2010

Mathematica

Select[Prime[Range[16000]],AllTrue[Rest[NestList[9#+8&,#,4]],PrimeQ]&] (* The program uses the AllTrue function from Mathematica version 10 *) (* Harvey P. Dale, Jun 25 2017 *)