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Numbers k such that k prefixed by '6' and followed by '3' is prime.
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%I #14 Aug 13 2024 11:14:32

%S 1,4,5,7,8,11,13,14,16,17,20,26,32,34,35,37,47,55,56,65,67,70,73,76,

%T 79,80,82,83,86,88,98,104,115,122,125,128,133,134,136,140,146,148,149,

%U 154,155,158,160,161,164,167,170,172,181,184,193,200,205,214,221

%N Numbers k such that k prefixed by '6' and followed by '3' is prime.

%H Harvey P. Dale, <a href="/A032714/b032714.txt">Table of n, a(n) for n = 1..1000</a>

%t Select[Range[300],PrimeQ[FromDigits[Join[{6},IntegerDigits[#],{3}]]]&] (* _Harvey P. Dale_, Mar 09 2013 *)

%Y Cf. A032702-A032733.

%K nonn,base

%O 1,2

%A _Patrick De Geest_, May 15 1998

%E Offset changed by _Andrew Howroyd_, Aug 13 2024