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A065568
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Sum over all subsets of {1,..,n} of the GCD of the subset.
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2
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1, 4, 10, 22, 42, 84, 154, 298, 568, 1108, 2142, 4254, 8362, 16636, 33076, 66004, 131556, 262974, 525136, 1050016, 2098756, 4196962, 8391288, 16782312, 33559612, 67118176, 134227594, 268453714, 536889198, 1073777718, 2147519572
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,2
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MATHEMATICA
| a(n)=Sum[Plus @@ GCD @@@ KSubsets[Range[n], m], {m, n}] or a(n)=Table[Sum[Plus@@(EulerPhi[Divisors[k]] 2^(k/Divisors[k]))/2, {k, n}], {n, 42}]
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CROSSREFS
| Row sums of A065567, first differences equal A034738,
Sequence in context: A023609 A055364 A032191 * A007825 A008256 A006001
Adjacent sequences: A065565 A065566 A065567 * A065569 A065570 A065571
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KEYWORD
| nonn
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AUTHOR
| Wouter Meeussen (wouter.meeussen(AT)pandora.be), Nov 30 2001
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