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A032623 Numbers k such that k concatenated with k+8 is a prime. 3
1, 3, 13, 15, 21, 39, 49, 55, 69, 75, 91, 111, 115, 159, 163, 165, 169, 171, 183, 193, 195, 199, 201, 205, 211, 229, 235, 241, 249, 265, 271, 273, 289, 291, 309, 313, 319, 321, 325, 331, 333, 349, 351, 355, 363, 379, 381, 385, 391, 393, 405, 423, 441, 445 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,2
LINKS
MATHEMATICA
Select[Range[500], PrimeQ[FromDigits[Flatten[IntegerDigits/@{#, #+8}]]]&] (* Harvey P. Dale, Nov 25 2023 *)
CROSSREFS
Cf. A032613.
Sequence in context: A230508 A045233 A113487 * A146512 A082704 A353060
KEYWORD
nonn,base
AUTHOR
Patrick De Geest, May 15 1998
STATUS
approved

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Last modified March 28 18:04 EDT 2024. Contains 371254 sequences. (Running on oeis4.)