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Numbers k such that 9*k - 4 is prime.
1

%I #19 Sep 08 2022 08:44:48

%S 1,3,5,7,13,15,17,19,27,29,33,35,39,43,45,47,55,57,63,67,69,73,83,85,

%T 89,99,105,109,113,115,117,123,133,137,143,145,147,153,157,159,165,

%U 167,173,175,179,189,193,199,203,209,213,215,217,223,227,235,237,249,253,257,265,267

%N Numbers k such that 9*k - 4 is prime.

%H Vincenzo Librandi, <a href="/A024909/b024909.txt">Table of n, a(n) for n = 1..1000</a>

%t Select[Range[400], PrimeQ[9# - 4] &] (* _Vincenzo Librandi_, Sep 26 2012 *)

%o (Magma) [n: n in [1..300] | IsPrime(9*n-4)]; // _Vincenzo Librandi_, Nov 19 2010

%o (PARI) is(n)=isprime(9*n-4) \\ _Charles R Greathouse IV_, Jun 06 2017

%Y Cf. A061240 (associated primes).

%K nonn,easy

%O 1,2

%A _Clark Kimberling_