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Search: id:A135268
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| A135268 |
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a(0) = 1; a(n) = a(n-1)+n-gcd(n,a(n-1)). |
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+0
1
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| 1, 1, 2, 4, 4, 8, 12, 18, 24, 30, 30, 40, 48, 60, 72, 84, 96, 112, 128, 146, 164, 184, 204, 226, 248, 272, 296, 322, 336, 364, 392, 422, 452, 484, 516, 550, 584, 620, 656, 694, 732, 772, 812, 854, 896, 940, 984, 1030, 1076, 1124, 1172
(list; graph; listen)
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OFFSET
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0,3
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FORMULA
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a(n)=c*n*(n-1), where c ~ 0.48....
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EXAMPLE
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a(8)=18+8-gcd(8,18)=18+8-2=24.
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MAPLE
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a[0]:=1: for n to 50 do a[n]:=a[n-1]+n-gcd(n, a[n-1]) end do: seq(a[n], n=0.. 50); - Emeric Deutsch (deutsch(AT)duke.poly.edu), Feb 28 2008
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CROSSREFS
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Adjacent sequences: A135265 A135266 A135267 this_sequence A135269 A135270 A135271
Sequence in context: A055946 A130124 A076342 this_sequence A131771 A047073 A069753
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KEYWORD
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easy,nonn
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AUTHOR
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Ctibor O. ZIZKA (ctibor.zizka(AT)seznam.cz), Feb 15 2008, Feb 21 2008
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EXTENSIONS
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Corrected and extended by Emeric Deutsch (deutsch(AT)duke.poly.edu), Feb 28 2008
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