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URL: https://oeis.org/A139487

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A139487
Numbers k such that 8k + 7 is prime.
11
0, 2, 3, 5, 8, 9, 12, 15, 18, 20, 23, 24, 27, 29, 32, 33, 38, 44, 45, 47, 53, 54, 57, 59, 60, 62, 74, 75, 78, 80, 89, 90, 92, 93, 102, 104, 107, 110, 113, 114, 120, 122, 123, 128, 129, 132, 135, 137, 143, 152, 153, 159, 162, 164, 165, 170, 174, 177, 179, 180, 183, 185
OFFSET
1,2
COMMENTS
For numbers k such that:
8k+1 is prime see A005123, primes see A007519;
8k+3 is prime see A005124, primes see A007520;
8k+5 is prime see A105133, primes see A007521;
8k+7 is prime see A139487, primes see A007522.
8k + 7 divides A000225(4k+3). - Jinyuan Wang, Mar 08 2019
LINKS
FORMULA
a(n) = (A007522(n) - 7)/8, n >= 1.
MATHEMATICA
a = {}; Do[If[PrimeQ[8 n + 7], AppendTo[a, n]], {n, 0, 300}]; a
Select[Range[0, 200], PrimeQ[8#+7]&] (* Harvey P. Dale, Oct 10 2012 *)
PROG
(Magma) [n: n in [0..200] | IsPrime(8*n+7)]; // Vincenzo Librandi, Jun 25 2014
(PARI) is(n)=isprime(8*n+7) \\ Charles R Greathouse IV, Feb 17 2017
KEYWORD
nonn,easy
AUTHOR
Artur Jasinski, Apr 23 2008
STATUS
approved