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Search: id:A084709
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| A084709 |
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a(1) = 4, for n > 1, a(n) = smallest multiple of a(n-1) such that a(n)-1 and a(n)+1 are twin primes. |
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1
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| 4, 12, 60, 180, 1620, 9720, 417960, 7523280, 308454480, 25293267360, 1593475843680, 74893364652960, 4793175337789440, 517662936481259520, 21224180395731640320, 4075042635980474941440, 611256395397071241216000
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OFFSET
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1,1
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MATHEMATICA
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a[1] = 4; a[n_] := a[n] = Block[{k = 2}, While[ !PrimeQ[ k*a[n - 1] - 1] || !PrimeQ[ k*a[n - 1] + 1], k++ ]; k*a[n - 1]]; Table[ a[n], {n, 1, 17}]
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CROSSREFS
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Adjacent sequences: A084706 A084707 A084708 this_sequence A084710 A084711 A084712
Sequence in context: A068525 A067755 A051858 this_sequence A057394 A054719 A083484
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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), Jun 09 2003
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EXTENSIONS
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Edited and extended by Robert G. Wilson v (rgwv(AT)rgwv.com), Jun 15 2003
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