A342389 - OEIS

A342389

a(n) = Sum_{k=1..n} k^gcd(k,n).

1, 5, 30, 264, 3135, 46709, 823564, 16777528, 387420759, 10000003265, 285311670666, 8916100500148, 302875106592331, 11112006826381965, 437893890380965260, 18446744073726350224, 827240261886336764313, 39346408075296928032645

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OFFSET

1,2

LINKS

Table of n, a(n) for n=1..18.

FORMULA

If p is prime, a(p) = A000217(p-1) + p^p = (p-1)*p/2 + p^p.

MATHEMATICA

a[n_] := Sum[k^GCD[k, n], {k, 1, n}]; Array[a, 18] (* Amiram Eldar, Mar 10 2021 *)

PROG

(PARI) a(n) = sum(k=1, n, k^gcd(k, n));

CROSSREFS

Cf. A000217, A228640, A342394, A342395.

Sequence in context: A245247 A353547 A199131 * A344525 A277464 A258300

Adjacent sequences: A342386 A342387 A342388 * A342390 A342391 A342392

KEYWORD

nonn,easy

AUTHOR

Seiichi Manyama, Mar 10 2021

STATUS

approved