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%I #5 May 03 2021 21:32:24
%S 1,1,-1,-1,0,-1,1,0,1,0,1,0,0,1,0,0,0,1,0,0,0,1,1,0,0,0,0,0,0,0,-1,0,
%T 0,0,0,0,0,0,0,0,0,0,-1,0,0,1,1,0,-1,0,0,0,0,0,0,0,0,0,1,0,0,-1,0,0,0,
%U 0,-1,0,0,0,-1,0,0,0,0,0,0,0,-1,0,0,0,1,0,0,-1,0,0,0,0
%N a(n) = mu(phi(n)), where mu is the Möbius function and phi is the Euler totient function.
%F a(n) = A008683(A000010(n)).
%t Table[MoebiusMu[EulerPhi[n]], {n, 100}]
%Y Cf. A000010 (phi), A008683 (mu).
%K sign
%O 1
%A _Wesley Ivan Hurt_, May 03 2021