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Numbers k such that 7*k - 5 is prime.
1

%I #23 Sep 08 2022 08:44:48

%S 1,4,6,12,16,22,24,28,34,46,48,52,54,58,64,66,72,78,82,94,102,108,118,

%T 124,126,132,136,148,156,162,168,174,184,186,196,198,202,204,208,214,

%U 222,232,252,256,258,268,274,286,288,292,294,298,306,312,316,318,334,336,342,346

%N Numbers k such that 7*k - 5 is prime.

%H Vincenzo Librandi, <a href="/A024904/b024904.txt">Table of n, a(n) for n = 1..1000</a>

%t Select[Range[400], PrimeQ[7 # - 5] &] (* _Vincenzo Librandi_, Sep 26 2012 *)

%o (Magma) [n: n in [1..1000] |IsPrime(7*n-5)]; // _Vincenzo Librandi_, Nov 20 2010

%o (PARI) is(n)=isprime(7*n-5) \\ _Charles R Greathouse IV_, Jun 06 2017

%Y Cf. A045392 (associated primes).

%K nonn,easy

%O 1,2

%A _Clark Kimberling_