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Search: id:A090530
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| A090530 |
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Least multiple k of prime(n) such that (k-1,k+1) forms a twin prime pair, or 0 if no such number exists. |
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+0
2
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| 4, 6, 30, 42, 198, 312, 102, 228, 138, 348, 1302, 1998, 1230, 1032, 282, 6360, 1062, 15738, 1608, 1278, 6132, 10428, 4482, 4272, 11058, 4242, 618, 642, 5232, 2712, 18288, 3930, 822, 1668, 1788, 11778, 3768, 5868, 5010, 9342, 23628, 3258, 17190
(list; graph; listen)
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OFFSET
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1,1
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COMMENT
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a(n) is a multiple of 6*prime(n) for n>2. Conjecture: No term is zero.
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EXAMPLE
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a(5) = 198 = 11*18, (197,199) forms a twin prime pair.
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MATHEMATICA
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For[n = 1, n < 40, n++, a := Prime[n]; k := 2; While[Not[PrimeQ[k*a + 1] && PrimeQ[k*a - 1]], k += 2]; Print[k*a]] - Stefan Steinerberger (stefan.steinerberger(AT)gmail.com), Feb 17 2006
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CROSSREFS
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Cf. A090531.
Sequence in context: A122113 A056221 A046849 this_sequence A093121 A136351 A075590
Adjacent sequences: A090527 A090528 A090529 this_sequence A090531 A090532 A090533
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KEYWORD
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nonn
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AUTHOR
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Amarnath Murthy (amarnath_murthy(AT)yahoo.com), Dec 07 2003
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EXTENSIONS
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More terms from David Wasserman (wasserma(AT)spawar.navy.mil), Dec 21 2005
More terms from Stefan Steinerberger (stefan.steinerberger(AT)gmail.com), Feb 17 2006
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