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A032723 Numbers k such that k prefixed by '6' and followed by '7' is a prime. 0
0, 1, 4, 7, 19, 21, 24, 25, 27, 28, 31, 33, 36, 39, 42, 54, 57, 60, 63, 73, 82, 85, 90, 91, 94, 96, 97, 99, 100, 102, 105, 129, 135, 141, 148, 150, 154, 162, 163, 165, 166, 168, 171, 175, 183, 192, 196, 198, 201, 204, 205, 213, 220, 229, 232, 234, 241, 246, 247 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,3

LINKS

Table of n, a(n) for n=1..59.

MATHEMATICA

Select[Range[0, 300], PrimeQ[FromDigits[Join[{6}, IntegerDigits[#], {7}]]]&] (* Harvey P. Dale, Mar 23 2015 *)

CROSSREFS

Sequence in context: A230601 A132207 A097537 * A231374 A173017 A063605

Adjacent sequences:  A032720 A032721 A032722 * A032724 A032725 A032726

KEYWORD

nonn,base

AUTHOR

Patrick De Geest, May 15 1998

STATUS

approved

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Last modified May 21 00:36 EDT 2022. Contains 353886 sequences. (Running on oeis4.)