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%I #12 Sep 08 2022 08:45:19
%S 1,31,59,83,97,157,193,197,233,289,347,367,409,431,439,443,547,683,
%T 701,731,733,769,781,787,797,839,877,961,1019,1039,1061,1123,1177,
%U 1181,1213,1249,1277,1283,1301,1349,1373,1423,1457,1579,1649,1667,1721
%N Numbers k such that the string 235723572357k is prime.
%H Harvey P. Dale, <a href="/A109356/b109356.txt">Table of n, a(n) for n = 1..1000</a>
%e If k=1 then 235723572357k = 2357235723571 (prime).
%e If k=289 then 235723572357k = 235723572357289 (prime).
%t Select[Range[2000],PrimeQ[235723572357*10^IntegerLength[#]+#]&] (* _Harvey P. Dale_, Aug 10 2017 *)
%o (Magma) [ n: n in [1..1750] | IsPrime(Seqint(Intseq(n) cat [7, 5, 3, 2, 7, 5, 3, 2, 7, 5, 3, 2])) ]; // _Vincenzo Librandi_, Feb 02 2011
%K nonn,base
%O 1,2
%A _Parthasarathy Nambi_, Aug 22 2005
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