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%I #11 Nov 27 2017 19:20:00
%S -1,-1,0,0,0,0,2,0,2,0,2,0,4,2,0,0,0,2,6,0,4,2,2,0,4,4,6,4,4,0,14,0,4,
%T 0,8,4,12,6,8,0,8,4,18,4,8,2,2,0,18,4,0,8,4,6,8,8,12,4,2,0,28,14,12,0,
%U 16,4,26,0,4,8,22,8,24,12,8,12,28,8,30,0,18,8,2,8,0,18,8,8,8,8,24,4,28,2,24,0,32
%N a(n) = phi(n) - 2*phi(phi(n)), where phi = Euler totient function, A000010.
%H Antti Karttunen, <a href="/A293516/b293516.txt">Table of n, a(n) for n = 1..65537</a>
%F a(n) = A000010(n) - 2*A010554(n).
%F a(n) = A070556(n) - A010554(n).
%F a(n) = -A083254(A000010(n)).
%o (PARI) A293516(n) = (eulerphi(n) - 2*eulerphi(eulerphi(n)));
%Y Cf. A000010, A010554, A051953, A070556, A083254, A295660.
%Y Cf. A003401 (gives the positions of zeros after the two initial -1's).
%K sign
%O 1,7
%A _Antti Karttunen_, Nov 27 2017
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