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A342539
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a(n) = Sum_{k=1..n} phi(gcd(k, n))^n.
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4
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1, 2, 10, 19, 1028, 132, 279942, 65798, 10078726, 2097160, 100000000010, 16797702, 106993205379084, 156728328204, 35186519703560, 281479271809036, 295147905179352825872, 203119914385420, 708235345355337676357650, 1152924803145924620, 46005163783270994804748, 20000000000000000000020
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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(n/d) * phi(d)^n.
If p is prime, a(p) = p-1 + (p-1)^p.
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MATHEMATICA
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a[n_] := DivisorSum[n, EulerPhi[n/#] * EulerPhi[#]^n &]; Array[a, 20] (* Amiram Eldar, Mar 15 2021 *)
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PROG
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(PARI) a(n) = sum(k=1, n, eulerphi(gcd(k, n))^n);
(PARI) a(n) = sumdiv(n, d, eulerphi(n/d)*eulerphi(d)^n);
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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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