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 A032703 n prefixed by '3' and followed by '1' is a prime. 1
 1, 3, 12, 18, 19, 22, 25, 27, 30, 33, 36, 37, 39, 46, 49, 51, 54, 57, 58, 63, 67, 69, 70, 76, 82, 85, 88, 91, 93, 105, 108, 109, 112, 115, 118, 123, 127, 132, 139, 148, 151, 153, 154, 160, 172, 174, 175, 177, 189, 198, 199, 205, 214, 219, 225, 226, 232, 234 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 LINKS Robert Israel, Table of n, a(n) for n = 1..10000 MAPLE seq(op(select(x -> isprime(3*10^d+10*x+1), [\$10^(d-2)..10^(d-1)-1])), d=2..4); # Robert Israel, Oct 22 2018 MATHEMATICA Select[Range[250], PrimeQ[FromDigits[Join[{3}, IntegerDigits[#], {1}]]]&] (* Harvey P. Dale, Mar 28 2011 *) CROSSREFS Sequence in context: A047906 A342776 A104641 * A234904 A284806 A125821 Adjacent sequences: A032700 A032701 A032702 * A032704 A032705 A032706 KEYWORD nonn,base AUTHOR Patrick De Geest, May 15 1998 EXTENSIONS Offset changed to 1 by Robert Israel, Oct 22 2018 STATUS approved

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Last modified March 30 11:15 EDT 2023. Contains 361618 sequences. (Running on oeis4.)