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Search: id:A102688
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| A102688 |
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a(n) = (1/n)*Sum_{k=1..n} k*2^gcd(n,k). |
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+0
1
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| 2, 5, 10, 20, 36, 74, 134, 272, 526, 1052, 2058, 4160, 8204, 16466, 32824, 65696, 131088, 262490, 524306, 1049168, 2097316, 4195358, 8388630, 16779632, 33554516, 67112996, 134218282, 268443848, 536870940, 1073759432, 2147483678
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OFFSET
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1,1
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FORMULA
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a(n) = (A000079(n)+n*A000031(n))/2.
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MATHEMATICA
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f[n_] := Sum[k*2^GCD[n, k], {k, n}]/n; Table[ f[n], {n, 32}] (from Robert G. Wilson v Feb 12 2005)
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CROSSREFS
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Adjacent sequences: A102685 A102686 A102687 this_sequence A102689 A102690 A102691
Sequence in context: A121597 A000712 A032442 this_sequence A001629 A068034 A084215
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KEYWORD
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easy,nonn
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AUTHOR
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Vladeta Jovovic (vladeta(AT)Eunet.yu), Feb 03 2005
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EXTENSIONS
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More terms from Robert G. Wilson v (rgwv(AT)rgwv.com), Feb 12 2005
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