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A032724 Numbers k such that k prefixed by '8' and followed by '7' is prime. 0

%I

%S 2,5,7,8,11,14,16,23,28,29,31,37,38,44,46,52,53,59,62,64,67,70,73,74,

%T 80,83,86,88,101,104,107,109,115,119,130,145,151,152,154,163,164,166,

%U 167,170,172,173,181,184,193,196,200,203,206,220,221,223,226,230,238

%N Numbers k such that k prefixed by '8' and followed by '7' is prime.

%t Select[Range[0,240],PrimeQ@FromDigits[Join[{8},IntegerDigits@#,{7}]]&] (* _Giorgos Kalogeropoulos_, Jul 28 2021 *)

%Y Subsequence of A001651 (not divisible by 3).

%K nonn,base

%O 1,1

%A _Patrick De Geest_, May 15 1998

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Last modified May 28 02:55 EDT 2022. Contains 354110 sequences. (Running on oeis4.)