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a(n) = Sum_{d|n} n^phi(d).
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%I #9 Jun 29 2021 10:51:09

%S 1,4,12,24,630,84,117656,4176,531531,20020,25937424612,21192,

%T 23298085122494,15059100,2562941490,4295033120,48661191875666868498,

%U 68025132,104127350297911241532860,25600320440,7355827597153224,53119845582892,907846434775996175406740561352

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

%F a(prime(n)) = A104129(n). - _Michel Marcus_, Jun 29 2021

%e 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.

%t a[n_] := DivisorSum[n, n^EulerPhi[#] &]; Array[a, 23] (* _Amiram Eldar_, Jun 29 2021 *)

%o (PARI) a(n) = sumdiv(n, d, n^eulerphi(d)); \\ _Michel Marcus_, Jun 29 2021

%Y Cf. A000010 (phi), A104129.

%K nonn

%O 1,2

%A _Wesley Ivan Hurt_, Jun 28 2021