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A345893

a(n) = Sum_{d|n} n^phi(d).

1, 4, 12, 24, 630, 84, 117656, 4176, 531531, 20020, 25937424612, 21192, 23298085122494, 15059100, 2562941490, 4295033120, 48661191875666868498, 68025132, 104127350297911241532860, 25600320440, 7355827597153224, 53119845582892, 907846434775996175406740561352

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OFFSET

1,2

LINKS

Table of n, a(n) for n=1..23.

FORMULA

a(prime(n)) = A104129(n). - Michel Marcus, Jun 29 2021

EXAMPLE

a(6) = Sum_{d|6} 6^phi(d) = 6^phi(1) + 6^phi(2) + 6^phi(3) + 6^phi(6) = 6^1 + 6^1 + 6^2 + 6^2 = 84.

MATHEMATICA

a[n_] := DivisorSum[n, n^EulerPhi[#] &]; Array[a, 23] (* Amiram Eldar, Jun 29 2021 *)

PROG