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A154886
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Number of ways to partition n into reduced fractions i/j with j<=n.
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3
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1, 5, 51, 655, 20980, 578779, 46097340, 2889706132, 485416306983, 68334145684271, 24330218582223815, 3847311627258606534, 2716890193805515507433, 1270766589764097820833691, 2188031110546839992589840986, 1331298554328475793875243619997
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,2
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LINKS
| Robert Gerbicz, Table of n, a(n) for n = 1..43
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EXAMPLE
| a(2) = #{2, 3/2+1/2, 1+1, 1+1/2+1/2, 1/2+1/2+1/2+1/2} = 5.
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MATHEMATICA
| modifiedFarey[n_] := Union@ Flatten@ Table[a/b, {b, n}, {a, b*n}]; t[n_, k_] := Length@ IntegerPartitions[n, {k}, modifiedFarey@ n]; Plus @@@ Table[t[n, k], {n, 7, 7}, {k, n*(Plus @@ EulerPhi@ Range@n)}] [From Robert G. Wilson v (rgwv(AT)rgwv.com), Aug 30 2010]
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CROSSREFS
| Cf. A154887, A119983, A143270.
Sequence in context: A041040 A180511 A190734 * A145162 A187235 A095839
Adjacent sequences: A154883 A154884 A154885 * A154887 A154888 A154889
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KEYWORD
| nonn
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AUTHOR
| Reinhard Zumkeller (reinhard.zumkeller(AT)gmail.com), Jan 17 2009
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EXTENSIONS
| a(7) from Robert G. Wilson v (rgwv(AT)rgwv.com), Aug 30 2010
a(8)-a(43) from Robert Gerbicz (robert.gerbicz(AT)gmail.com), Nov 19 2010
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