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Search: id:A065568
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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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+0
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
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OFFSET
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1,2
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MATHEMATICA
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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
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Row sums of A065567, first differences equal A034738,
Sequence in context: A023609 A055364 A032191 this_sequence A007825 A008256 A006001
Adjacent sequences: A065565 A065566 A065567 this_sequence A065569 A065570 A065571
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KEYWORD
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nonn
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AUTHOR
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Wouter Meeussen (wouter.meeussen(AT)pandora.be), Nov 30 2001
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