A023266 Primes that remain prime through 2 iterations of function f(x) = 9x + 4.

3, 7, 31, 37, 41, 71, 73, 83, 107, 191, 283, 307, 317, 337, 373, 421, 631, 743, 773, 821, 857, 883, 967, 1283, 1297, 1361, 1451, 1567, 1571, 1637, 1823, 1973, 2137, 2207, 2351, 2417, 2677, 2683, 2837, 3011, 3083, 3271, 3331, 3517, 3571, 3691, 3727, 3793, 3877

Offset: 1

Author

David W. Wilson

Keywords

• nonn

Comments

Primes p such that 9*p+4 and 81*p+40 are also primes. - Vincenzo Librandi, Aug 04 2010

Links

• Harvey P. Dale, Table of n, a(n) for n = 1..10000

Programs

Magma

[n: n in [1..100000] | IsPrime(n) and IsPrime(9*n+4) and IsPrime(81*n+40)] // Vincenzo Librandi, Aug 04 2010

Mathematica

Select[Prime[Range[600]],AllTrue[Rest[NestList[9#+4&,#,2]],PrimeQ]&] (* The program uses the AllTrue function from Mathematica version 10 *) (* Harvey P. Dale, Jul 15 2016 *)