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A068963
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Sum(phi(d^3)); d|n.
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2
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1, 5, 19, 37, 101, 95, 295, 293, 505, 505, 1211, 703, 2029, 1475, 1919, 2341, 4625, 2525, 6499, 3737, 5605, 6055, 11639, 5567, 12601, 10145, 13627, 10915, 23549, 9595, 28831, 18725, 23009, 23125, 29795, 18685, 49285, 32495, 38551, 29593
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OFFSET
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1,2
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LINKS
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Harvey P. Dale, Table of n, a(n) for n = 1..1000
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FORMULA
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Also Sum(d*phi(d^2)), d|n; or Sum(d^2*phi(d)); d|n
Also Sum_{k=1..n} (n/gcd(n, k))^2 = Sum_{k=1..n} (lcm(n, k)/k)^2. - Vladeta Jovovic, Dec 29 2002
Multiplicative with a(p^e) = 1 + p^2 + (p-1)(p^(3e)-1)/(p^3-1)
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MATHEMATICA
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Table[Total[EulerPhi[Divisors[n]^3]], {n, 50}] (* Harvey P. Dale, Feb 24 2013 *)
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CROSSREFS
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Cf. A057660, A056789.
Sequence in context: A213631 A031093 A146861 * A129828 A146600 A031379
Adjacent sequences: A068960 A068961 A068962 * A068964 A068965 A068966
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KEYWORD
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easy,nonn,mult
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AUTHOR
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Benoit Cloitre, Apr 06 2002
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STATUS
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approved
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