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A072569 Odd interprimes. 24
9, 15, 21, 39, 45, 69, 81, 93, 99, 105, 111, 129, 165, 195, 205, 217, 225, 231, 279, 309, 315, 351, 363, 381, 393, 399, 405, 441, 453, 459, 465, 473, 483, 489, 495, 501, 515, 615, 625, 645, 667, 675, 687, 705, 723, 741, 747, 759, 765, 771, 803, 825, 855, 861 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,1
COMMENTS
The interprimes (A024675) are those integers that lie at the midpoint between consecutive odd primes.
LINKS
Eric Weisstein's World of Mathematics, Interprime
MATHEMATICA
a = Table[ Prime[n], {n, 2, 200}]; b = {}; Do[d = (a[[n + 1]] - a[[n]])/2; If[ OddQ[ a[[n]] + d], b = Append[b, a[[n]] + d]], {n, 1, 198}]; b
Select[Plus @@@ Partition[Table[Prime[n], {n, 2, 100}], 2, 1]/2, OddQ]
Select[Mean/@Partition[Prime[Range[2, 200]], 2, 1], OddQ] (* Harvey P. Dale, Jan 22 2019 *)
CROSSREFS
Odd members of A024675. Sequence is union of A072572 and A072573.
Sequence in context: A063174 A338082 A336115 * A072572 A029708 A125215
KEYWORD
nonn
AUTHOR
Marco Matosic, Jun 24 2002
EXTENSIONS
Edited by N. J. A. Sloane and Robert G. Wilson v, Jun 27 2002
STATUS
approved

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Last modified July 20 13:32 EDT 2024. Contains 374445 sequences. (Running on oeis4.)