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A344525 a(n) = Sum_{1 <= x_1, x_2, ... , x_n <= n} gcd(x_1,x_2, ... ,x_n). 6
1, 5, 30, 276, 3165, 47521, 826000, 16843792, 387723045, 10009889889, 285360865350, 8918311872516, 302888304741841, 11112685595264369, 437898699063881208, 18447025862624951488, 827242515246907227633, 39346558373191515582161 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

LINKS

Seiichi Manyama, Table of n, a(n) for n = 1..386

FORMULA

a(n) = Sum_{k=1..n} phi(k) * floor(n/k)^n.

a(n) ~ n^n. - Vaclav Kotesovec, May 23 2021

MATHEMATICA

a[n_] := Sum[EulerPhi[k] * Quotient[n, k]^n, {k, 1, n}]; Array[a, 20] (* Amiram Eldar, May 22 2021 *)

PROG

(PARI) a(n) = sum(k=1, n, eulerphi(k)*(n\k)^n);

CROSSREFS

Main diagonal of A344479.

Cf. A018806, A344140, A344522, A344523, A344524.

Sequence in context: A245247 A199131 A342389 * A277464 A258300 A276752

Adjacent sequences:  A344522 A344523 A344524 * A344526 A344527 A344528

KEYWORD

nonn

AUTHOR

Seiichi Manyama, May 22 2021

STATUS

approved

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Last modified May 23 10:51 EDT 2022. Contains 353975 sequences. (Running on oeis4.)