A366562 - OEIS

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A366562

a(n) = Sum_{k=1..n} A366561(n,k)*A023900(k)/n.

1, 0, -2, 0, -4, 0, -6, 0, -6, 0, -10, 0, -12, 0, 8, 0, -16, 0, -18, 0, 12, 0, -22, 0, -20, 0, -18, 0, -28, 0, -30, 0, 20, 0, 24, 0, -36, 0, 24, 0, -40, 0, -42, 0, 24, 0, -46, 0, -42, 0, 32, 0, -52, 0, 40, 0, 36, 0, -58, 0, -60, 0, 36, 0, 48, 0, -66, 0, 44, 0, -70, 0, -72, 0

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OFFSET

1,3

LINKS

Table of n, a(n) for n=1..74.

FORMULA

a(n) = Sum_{k=1..n} A366561(n,k)*A023900(k)/n.

Conjecture: a(n) = [Mod[n, 2] = 1]*A000010(n)*(-1)^A001221(n).

MATHEMATICA

nn = 74; f = x^2 - y^2; g[n_] := DivisorSum[n, MoebiusMu[#] # &]; Table[Sum[Sum[Sum[If[GCD[f, n] == k, 1, 0]*g[k]/n, {x, 1, n}], {y, 1, n}], {k, 1, n}], {n, 1, nn}]

CROSSREFS

Cf. A000010, A001221, A366561, A366563.

Sequence in context: A119690 A166260 A319813 * A071648 A001613 A237420

Adjacent sequences: A366559 A366560 A366561 * A366563 A366564 A366565

KEYWORD

sign

AUTHOR

Mats Granvik, Oct 13 2023

STATUS

approved