login
Numbers k such that 10*k - 7 is prime.
1

%I #32 Oct 23 2024 13:55:45

%S 1,2,3,5,6,8,9,11,12,17,18,20,23,24,27,29,30,32,36,38,39,44,45,47,51,

%T 53,57,60,62,65,66,68,69,74,75,78,83,86,87,89,96,99,102,104,107,110,

%U 111,113,116,117,120,122,123,129,131,138,143,144,146,149,150,153,155,156,159,162,167

%N Numbers k such that 10*k - 7 is prime.

%H Vincenzo Librandi, <a href="/A024913/b024913.txt">Table of n, a(n) for n = 1..1000</a>

%t Select[Range[500], PrimeQ[10 # - 7] &] (* _Vincenzo Librandi_, May 19 2014 *)

%o (Magma) [n: n in [1..1000] |IsPrime(10*n-7)]; // _Vincenzo Librandi_, Nov 19 2010

%o (PARI) is(n)=isprime(10*n-7) \\ _Charles R Greathouse IV_, Jun 06 2017

%Y Cf. A030431 (associated primes).

%K nonn,easy

%O 1,2

%A _Clark Kimberling_