A023353 Primes that remain prime through 5 iterations of the function f(x) = 9x + 4.

421, 773, 1567, 4111, 68447, 75721, 111373, 127301, 137927, 140321, 156593, 170767, 177131, 192341, 194687, 202637, 240641, 254407, 254963, 308303, 321821, 332951, 395431, 464131, 515663, 710081, 822893, 856393, 989533, 997123, 1012201, 1047077

Offset: 1

Author

David W. Wilson

Keywords

• nonn

Comments

Primes p such that 9*p+4, 81*p+40, 729*p+364, 6561*p+3280 and 59049*p+29524 are also primes. - Vincenzo Librandi, Aug 05 2010

Links

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

Crossrefs

Subsequence of A023234, A023266, A023297, and A023325.

Programs

Magma

[n: n in [1..19000000] | IsPrime(n) and IsPrime(9*n+4) and IsPrime(81*n+40) and IsPrime(729*n+364) and IsPrime(6561*n+3280) and IsPrime(59049*n+29524)] // Vincenzo Librandi, Aug 05 2010

Mathematica

okQ[n_]:=And@@PrimeQ/@Rest[NestList[9#+4&,n,5]]; Select[Prime[Range[100000]],okQ]  (* Harvey P. Dale, Jan 29 2011 *)