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A342543
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a(n) = Sum_{k=1..n} phi(gcd(k, n))^gcd(k, n).
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4
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1, 2, 10, 19, 1028, 76, 279942, 65558, 10077718, 1049608, 100000000010, 16777334, 106993205379084, 78364444044, 35184372090920, 281474976776236, 295147905179352825872, 101559966746268, 708235345355337676357650, 1152921504607897676, 46005119909369702026044, 10000000000100000000020
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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)^d.
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[#]^# &]; 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))^gcd(k, n));
(PARI) a(n) = sumdiv(n, d, eulerphi(n/d)*eulerphi(d)^d);
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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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