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Numbers k such that k prefixed by '8' and followed by '1' is prime.
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%I #16 Aug 13 2024 11:50:11

%S 1,2,8,10,11,16,17,19,22,23,29,31,43,46,50,52,58,64,68,73,74,76,82,83,

%T 86,94,95,97,100,103,104,107,110,113,118,128,133,137,140,142,155,161,

%U 167,170,176,190,193,197,202,203,205,214,217,223,224,226,230,235

%N Numbers k such that k prefixed by '8' and followed by '1' is prime.

%t Select[Range[250],PrimeQ[FromDigits[Join[{8}, IntegerDigits[#],{1}]]]&] (* _Harvey P. Dale_, Mar 24 2011 *)

%Y Cf. A032702-A032733.

%K nonn,base

%O 1,2

%A _Patrick De Geest_, May 15 1998

%E Offset changed by _Andrew Howroyd_, Aug 11 2024