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%I #17 Jul 16 2022 13:20:42
%S 0,1,3,4,6,9,13,16,18,21,25,30,34,40,45,46,51,52,54,55,60,61,63,67,69,
%T 72,76,79,84,87,90,91,94,96,114,117,123,124,126,127,130,132,133,135,
%U 138,139,147,151,154,156,160,162,165,166,168,172,181,184,190,195
%N Integers that when prefixed by '3' and followed by '7' yield a prime.
%p q:= k-> isprime(parse(""||3||k||7)):
%p select(q, [$0..200])[]; # _Alois P. Heinz_, Jul 16 2022
%t Select[Range[0,250],PrimeQ[FromDigits[Join[{3},IntegerDigits[#],{7}]]]&] (* _Harvey P. Dale_, Dec 19 2010 *)
%o (PARI) isok(k) = isprime(eval(concat(3, concat(Str(k), 7)))); \\ _Michel Marcus_, Jul 16 2022
%K nonn,base
%O 1,3
%A _Patrick De Geest_, May 15 1998
%E Name edited and offset 1 from _Michel Marcus_, Jul 16 2022
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