Reminder: The OEIS is hiring a new managing editor, and the application deadline is January 26.
%I #15 Sep 08 2022 08:45:19
%S 7,13,17,23,29,31,41,47,71,83,101,107,137,157,169,193,197,217,221,223,
%T 259,301,347,373,389,391,403,427,437,469,491,497,511,527,559,563,581,
%U 587,613,631,653,673,679,683,689,701,703,727,743,749,757,799,827,833,857,893,899,907,917
%N Numbers k such that the string 10197k is prime.
%C 101 and 97 are primes.
%H Michael De Vlieger, <a href="/A108334/b108334.txt">Table of n, a(n) for n = 1..10000</a>
%e k=7 and k=83 are in the sequence because 10197k = 101977 and 10197k = 1019783 are prime.
%t Select[Range[10^3], PrimeQ[10197*10^IntegerLength[#] + #] &] (* _Michael De Vlieger_, Jan 22 2018 *)
%o (Magma) [ n: n in [1..1750] | IsPrime(Seqint(Intseq(n) cat [7, 9, 1, 0, 1])) ]; // _Vincenzo Librandi_, Feb 02 2011
%K nonn,base
%O 1,1
%A _Parthasarathy Nambi_, Jun 30 2005