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Search: id:A087859
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| A087859 |
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a(n) = the number of twin primes x-1,x+1 such that x=j*(p(n)#)/p(k), where 1<=j<p(n+1) and 1<=k<=n and p(k) doesn't divide j. |
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3
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| 0, 1, 3, 7, 8, 10, 15, 13, 13, 15, 10, 12, 15, 15, 18, 13, 22, 15, 23, 19, 23, 16, 19, 16, 22, 13, 15, 20, 23, 14, 18, 27, 20, 20, 16, 25, 21, 25, 14, 27, 21
(list; graph; listen)
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OFFSET
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1,3
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COMMENT
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p(n) is the n-th prime; # denotes primorial (A002110).
a(n) seems to grow like 4 log p(n).
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EXAMPLE
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a(3)=3 because for j,k=(1,3),(2,3),(3,3), j*(5#)/p(k)+-1 are primes.
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CROSSREFS
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Cf. A002110, A087941, A088968.
Sequence in context: A019270 A047357 A003607 this_sequence A050010 A106753 A062863
Adjacent sequences: A087856 A087857 A087858 this_sequence A087860 A087861 A087862
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KEYWORD
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nonn
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AUTHOR
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Pierre CAMI (colettecami(AT)aol.com), Oct 25 2003
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EXTENSIONS
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Edited by Don Reble (djr(AT)nk.ca), Nov 16 2005
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