

A032720


Integers that when prefixed by '3' and followed by '7' yield a prime.


0



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, 72, 76, 79, 84, 87, 90, 91, 94, 96, 114, 117, 123, 124, 126, 127, 130, 132, 133, 135, 138, 139, 147, 151, 154, 156, 160, 162, 165, 166, 168, 172, 181, 184, 190, 195
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OFFSET

1,3


LINKS



MAPLE

q:= k> isprime(parse(""3k7)):


MATHEMATICA

Select[Range[0, 250], PrimeQ[FromDigits[Join[{3}, IntegerDigits[#], {7}]]]&] (* Harvey P. Dale, Dec 19 2010 *)


PROG

(PARI) isok(k) = isprime(eval(concat(3, concat(Str(k), 7)))); \\ Michel Marcus, Jul 16 2022


CROSSREFS



KEYWORD

nonn,base


AUTHOR



EXTENSIONS



STATUS

approved



