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a(1) = 0, then after the first differences of A064415.
5

%I #9 Apr 18 2020 19:45:41

%S 0,1,0,1,0,0,0,1,-1,1,0,0,0,0,0,1,0,-1,0,1,-1,1,0,0,0,0,-1,1,0,0,0,1,

%T -1,1,-1,0,0,0,0,1,0,-1,0,1,-1,1,0,0,-1,1,0,0,0,-1,1,0,-1,1,0,0,0,0,

%U -1,2,-1,0,0,1,-1,0,0,0,0,0,0,0,0,0,0,1,-2,2,0,-1,1,-1,0,1,0,-1,0,1,-1,1,-1,1,0,-1,0,1,0,0,0,0,-1

%N a(1) = 0, then after the first differences of A064415.

%H Antti Karttunen, <a href="/A334195/b334195.txt">Table of n, a(n) for n = 1..65537</a>

%F a(1) = 0; and for n > 1, a(n) = A064415(n) - A064415(n-1).

%F a(n) = A334090(n) - A334091(n).

%o (PARI)

%o A003434(n) = for(k=0, n, n>1 || return(k); n=eulerphi(n));

%o A064415(n) = if(1==n,0, A003434(n)-(n%2));

%o A334195(n) = if(1==n,0,A064415(n)-A064415(n-1));

%Y Cf. A003434, A064415, A334090, A334091, A334196.

%Y Also, from a(3) onward the first differences of A054725.

%K sign

%O 1,64

%A _Antti Karttunen_, Apr 18 2020