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A023279
Primes that remain prime through 3 iterations of function f(x) = 3x + 8.
3
11, 31, 211, 1151, 3181, 5051, 5261, 6101, 6661, 9391, 9551, 10501, 11701, 13171, 15901, 16481, 19531, 22051, 24181, 26261, 27031, 28351, 28591, 28661, 29411, 30941, 31321, 32621, 38011, 40471, 42101, 48371, 49921, 57571, 59791, 61981, 66161, 67271
OFFSET
1,1
COMMENTS
Primes p such that 3*p+8, 9*p+32 and 27*p+104 are also primes. - Vincenzo Librandi, Aug 04 2010
FORMULA
a(n) == 1 (mod 10). - John Cerkan, Sep 16 2016
MATHEMATICA
Select[Prime@ Range@ 7000, Times @@ Boole@ PrimeQ@ Rest@ NestList[3 # + 8 &, #, 3] > 0 &] (* Michael De Vlieger, Sep 19 2016 *)
PROG
(Magma) [n: n in [1..150000] | IsPrime(n) and IsPrime(3*n+8) and IsPrime(9*n+32) and IsPrime(27*n+104)] // Vincenzo Librandi, Aug 04 2010
(PARI) is(n)=isprime(n) && isprime(3*n+8) && isprime(9*n+32) && isprime(27*n+104) \\ Charles R Greathouse IV, Sep 20 2016
CROSSREFS
Subsequence of A023210 and of A023248.
Sequence in context: A128337 A093382 A098264 * A068715 A093881 A328715
KEYWORD
nonn
STATUS
approved