%I #8 Aug 17 2021 16:11:32
%S 4,5,7,8,10,11,16,20,22,25,29,31,32,35,38,44,46,49,52,53,55,65,70,71,
%T 73,76,77,88,91,92,98,101,103,106,107,113,115,118,121,124,125,131,137,
%U 146,148,164,169,172,176,179,184,185,200,202,205,206,208,209,211
%N n prefixed by '3' and followed by '9' is a prime.
%H Harvey P. Dale, <a href="/A032728/b032728.txt">Table of n, a(n) for n = 0..1000</a>
%t Select[Range[250],PrimeQ[FromDigits[Join[{3},IntegerDigits[#],{9}]]]&] (* _Harvey P. Dale_, Aug 17 2021 *)
%K nonn,base
%O 0,1
%A _Patrick De Geest_, May 15 1998
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