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%I #9 Sep 13 2023 23:11:54
%S 0,-1,-1,0,-1,-2,-1,2,3,-2,-1,0,-1,-2,1,6,-1,2,-1,2,3,-2,-1,4,15,-2,
%T 15,4,-1,0,-1,14,7,-2,13,8,-1,-2,9,10,-1,2,-1,8,17,-2,-1,12,35,14,13,
%U 10,-1,14,25,16,15,-2,-1,8,-1,-2,27,30,31,6,-1,14,19,12
%N a(n) = Sum_{k=1..n} A191898(n,k)*[A191904(n,k) = A191898(n,k)].
%F a(n) = Sum_{k=1..n} A191898(n,k)*[A191904(n,k) = A191898(n,k)].
%F Conjecture: a(n) = A057859(n) - A008472(n) - 1.
%t f[n_] := DivisorSum[n, MoebiusMu[#] # &]; Table[Sum[If[If[Mod[n, k] == 0, 1 - k, 1] == f[GCD[n, k]], f[GCD[n, k]], 0], {k, 1, n}], {n, 1, 70}]
%Y Cf. A191898, A191904, A057859, A008472.
%K sign
%O 1,6
%A _Mats Granvik_, Aug 13 2023
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