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Search: id:A111164
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| A111164 |
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Number of distinct integers of the form (n+k)/|(n-k)| for k>0. |
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+0
2
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| 2, 3, 5, 5, 6, 7, 6, 7, 9, 9, 6, 10, 6, 9, 12, 9, 6, 13, 6, 12, 13, 9, 6, 14, 10, 9, 13, 13, 6, 17, 6, 11, 13, 9, 13, 18, 6, 9, 13, 16, 6, 18, 6, 13, 20, 9, 6, 18, 10, 15, 13, 13, 6, 19, 14, 16, 13, 9, 6, 23, 6, 9, 20, 13, 14, 19, 6, 13, 13, 20, 6, 23, 6, 9, 20, 13, 14, 19, 6, 20, 17, 9, 6
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OFFSET
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1,1
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EXAMPLE
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For n=14 we have integer values of this form when k={7; 10; 12; 13; 15; 16; 18; 19; 21; 28; 42} and (14+k)/|(14-k)| = {3, 6, 13, 27, 29, 15, 8, 5, 3, 2}. Thus a(14) = 9 because 3 is present twice.
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MATHEMATICA
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f[n_] := Length[ Union[ Select[(n + #)/Abs[n - # ] & /@ Delete[ Range[ Floor[3n]], n], IntegerQ[ # ] &]]]; Array[f, 83] (* Robert G. Wilson v *)
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CROSSREFS
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Cf. A111150.
Sequence in context: A102642 A133304 A003660 this_sequence A029910 A063677 A078903
Adjacent sequences: A111161 A111162 A111163 this_sequence A111165 A111166 A111167
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KEYWORD
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easy,nonn
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AUTHOR
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Paolo P. Lava & Giorgio Balzarotti (ppl(AT)spl.at), Oct 21 2005
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EXTENSIONS
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Corrected and extended by Robert G. Wilson v (rgwv(at)rgwv.com), Oct 31 2005
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