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Search: id:A111150
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| A111150 |
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a(n) is the number of integers of the form (n+k)/|(n-k)| for k>0. |
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+0
3
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| 2, 4, 6, 6, 6, 10, 6, 8, 10, 10, 6, 14, 6, 10, 14, 10, 6, 16, 6, 14, 14, 10, 6, 18, 10, 10, 14, 14, 6, 22, 6, 12, 14, 10, 14, 22, 6, 10, 14, 18, 6, 22, 6, 14, 22, 10, 6, 22, 10, 16, 14, 14, 6, 22, 14, 18, 14, 10, 6, 30, 6, 10, 22, 14, 14, 22, 6, 14, 14, 22, 6, 28, 6, 10, 22, 14, 14, 22
(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)<=2^(n-1) & a(p)=6 for odd primes. - Robert G. Wilson v.
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EXAMPLE
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For n=7 we have integer value for the form when k={5; 6; 8; 9; 14; 21} and (7+k)/|(7-k)| = {6, 13, 15, 8, 3, 2}. Thus a(7) = 6.
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MATHEMATICA
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f[n_] := Length[ Select[(n + #)/Abs[n - # ] & /@ Delete[ Range[ Floor[5n/3]], n], IntegerQ[ # ] &]] + 2; Array[f, 78] (* Robert G. Wilson v *)
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CROSSREFS
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Sequence in context: A092337 A050823 A050825 this_sequence A166983 A078611 A131450
Adjacent sequences: A111147 A111148 A111149 this_sequence A111151 A111152 A111153
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KEYWORD
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easy,nonn
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AUTHOR
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Paolo P. Lava (ppl(AT)spl.at) & Giorgio Balzarotti (greenblue(AT)tiscali.it), Oct 19 2005
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EXTENSIONS
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Edited and extended by Robert G. Wilson v (rgwv(at)rgwv.com), Oct 19 2005
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