A023337 Primes that remain prime through 5 iterations of function f(x) = 3x + 8.
3181, 61981, 134291, 342821, 459091, 882451, 984931, 1016011, 1028471, 1181701, 1391561, 1897801, 2009311, 2272301, 2476421, 2769791, 3048041, 3085421, 3128821, 3207221, 3545111, 4092931, 4690591, 5015321, 5863651, 6027941, 6361351, 6796541
Offset: 1
Keywords
Links
- John Cerkan, Table of n, a(n) for n = 1..10000
Programs
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Magma
[n: n in [1..25000000] | IsPrime(n) and IsPrime(3*n+8) and IsPrime(9*n+32) and IsPrime(27*n+104) and IsPrime(81*n+320) and IsPrime(243*n+968)] // Vincenzo Librandi, Aug 05 2010
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Mathematica
Select[Prime[Range[500000]],And@@PrimeQ[Rest[NestList[3#+8&,#,5]]]&] (* Harvey P. Dale, Apr 07 2014 *)
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PARI
is(n)=isprime(n) && isprime(3*n+8) && isprime(9*n+32) && isprime(27*n+104) && isprime(81*n+320) && isprime(243*n+968) \\ Charles R Greathouse IV, Oct 11 2016
Formula
a(n) == 31 (mod 70). - John Cerkan, Oct 11 2016
Comments