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A034767
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Dirichlet convolution of phi(n) with Bell numbers.
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0
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1, 2, 4, 8, 19, 58, 209, 888, 4150, 21170, 115985, 678642, 4213609, 27644652, 190899368, 1382959444, 10480142163, 82864874064, 682076806177, 5832742226266, 51724158235802, 474869816272746, 4506715738447345
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OFFSET
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1,2
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LINKS
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FORMULA
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a(n) = Sum_{d|n} phi(d)*A000110(n/d) (by definition).
a(n) = Sum_{k=1..n} A000110(gcd(n,k)).
a(n) = Sum_{k=1..n} A000110(n/gcd(n,k))*phi(gcd(n,k))/phi(n/gcd(n,k)). (End)
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MATHEMATICA
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Table[Sum[BellB[n/d - 1]*EulerPhi[d], {d, Divisors[n]}], {n, 1, 25}] (* Vaclav Kotesovec, Sep 10 2019 *)
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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STATUS
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approved
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