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A141767
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A positive integer n is included if (p-1)*(p+1) divides n for every prime p that divides n.
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2
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24, 48, 72, 96, 120, 144, 192, 216, 240, 288, 336, 360, 384, 432, 480, 576, 600, 648, 672, 720, 768, 864, 960, 1008, 1080, 1152, 1200, 1296, 1320, 1344, 1440, 1536, 1680, 1728, 1800, 1920, 1944, 2016, 2160, 2304, 2352, 2400, 2592, 2640, 2688, 2880, 3000
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,1
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COMMENTS
| Every term is a multiple of 24.
Is A124240 also those positive integers n where p-1 divides n for every prime p that divides n?
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EXAMPLE
| 120 has the prime factorization of 2^3 * 3^1 * 5^1. The distinct primes dividing 120 are therefore 2,3,5. (2-1)*(2+1)=3, (3-1)*(3+1)=8 and (5-1)*(5+1)=24 all divide 120. So 120 is included in the sequence.
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MATHEMATICA
| fQ[n_] := Block[{p = First /@ FactorInteger@ n}, Union@ Mod[n, (p - 1) (p + 1)] == {0}]; Select[ Range[2, 3000], fQ@# &] [From Robert G. Wilson v (rgwv(AT)rgwv.com), May 25 2009]
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CROSSREFS
| Cf. A140470, A141766, A124240.
Sequence in context: A050497 A162282 A008606 * A183008 A054734 A174906
Adjacent sequences: A141764 A141765 A141766 * A141768 A141769 A141770
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KEYWORD
| nonn
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AUTHOR
| Leroy Quet Jul 02 2008
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EXTENSIONS
| Added missing term 336 and a(14)-a(47) from Donovan Johnson (donovan.johnson(AT)yahoo.com), Sep 27 2008
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