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A032726 Numbers k such that k prefixed by '1' and followed by '9' is a prime. 1
0, 3, 4, 7, 9, 10, 12, 22, 24, 25, 27, 28, 31, 39, 40, 42, 43, 45, 48, 49, 54, 55, 57, 60, 61, 66, 69, 70, 75, 78, 87, 88, 94, 97, 99, 105, 106, 111, 114, 115, 123, 127, 129, 132, 136, 139, 148, 151, 154, 157, 168, 169, 171, 177, 178, 183, 190, 193, 195, 196, 204 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

LINKS

Table of n, a(n) for n=1..61.

MATHEMATICA

Select[Range[0, 200], PrimeQ@FromDigits[Join[{1}, IntegerDigits@#, {9}]]&] (* Giorgos Kalogeropoulos, Jul 28 2021 *)

CROSSREFS

Sequence in context: A330178 A059010 A066928 * A029739 A005098 A185661

Adjacent sequences:  A032723 A032724 A032725 * A032727 A032728 A032729

KEYWORD

nonn,base

AUTHOR

Patrick De Geest, May 15 1998

STATUS

approved

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Last modified January 21 00:46 EST 2022. Contains 350473 sequences. (Running on oeis4.)