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A032724 Numbers k such that k prefixed by '8' and followed by '7' is prime. 0
2, 5, 7, 8, 11, 14, 16, 23, 28, 29, 31, 37, 38, 44, 46, 52, 53, 59, 62, 64, 67, 70, 73, 74, 80, 83, 86, 88, 101, 104, 107, 109, 115, 119, 130, 145, 151, 152, 154, 163, 164, 166, 167, 170, 172, 173, 181, 184, 193, 196, 200, 203, 206, 220, 221, 223, 226, 230, 238 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,1
LINKS
MATHEMATICA
Select[Range[0, 240], PrimeQ@FromDigits[Join[{8}, IntegerDigits@#, {7}]]&] (* Giorgos Kalogeropoulos, Jul 28 2021 *)
CROSSREFS
Subsequence of A001651 (not divisible by 3).
Sequence in context: A276545 A138671 A286693 * A153308 A370856 A216565
KEYWORD
nonn,base
AUTHOR
Patrick De Geest, May 15 1998
STATUS
approved

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Last modified May 29 04:26 EDT 2024. Contains 372921 sequences. (Running on oeis4.)