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Search: id:A072569
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| 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; listen)
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OFFSET
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1,1
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COMMENT
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The interprimes (A024675) are those integers that lie at the mid-point between consecutive odd primes.
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LINKS
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Eric Weisstein's World of Mathematics, Interprime
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FORMULA
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(P_n+1 - P_n)/2 is odd.
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MATHEMATICA
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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]
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CROSSREFS
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Odd members of A024675. Sequence is union of A072572 and A072573.
Cf. A024675, A072568.
Sequence in context: A033553 A020192 A063174 this_sequence A072572 A029708 A125215
Adjacent sequences: A072566 A072567 A072568 this_sequence A072570 A072571 A072572
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KEYWORD
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nonn
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AUTHOR
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Marco Matosic (marcomatosic(AT)hotmail.com), Jun 24 2002
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EXTENSIONS
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Edited by njas and Robert G. Wilson v (rgwv(AT)rgwv.com), Jun 27 2002
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