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Sum of A083254 (2*phi(n) - n) and its Dirichlet inverse.
3

%I #6 Feb 12 2019 22:37:35

%S 2,0,0,0,0,0,0,0,1,0,0,0,0,0,6,0,0,-4,0,0,10,0,0,0,9,0,5,0,0,-16,0,0,

%T 18,0,30,-4,0,0,22,0,0,-24,0,0,11,0,0,0,25,-12,30,0,0,-18,54,0,34,0,0,

%U -24,0,0,21,0,66,-40,0,0,42,-32,0,0,0,0,9,0,90,-48,0,0,19,0,0,-40,90,0,54,0,0,-38,110,0,58,0,102,0,0,-20

%N Sum of A083254 (2*phi(n) - n) and its Dirichlet inverse.

%H Antti Karttunen, <a href="/A323913/b323913.txt">Table of n, a(n) for n = 1..20000</a>

%o (PARI)

%o up_to = 16384;

%o DirInverse(v) = { my(u=vector(#v)); u[1] = (1/v[1]); for(n=2, #v, u[n] = -sumdiv(n, d, if(d<n, v[n/d]*u[d], 0))); (u) }; \\ Compute the Dirichlet inverse of the sequence given in input vector v.

%o A083254(n) = (2*eulerphi(n)-n);

%o v323912 = DirInverse(vector(up_to,n,A083254(n)));

%o A323912(n) = v323912[n];

%o A323913(n) = (A083254(n)+A323912(n));

%Y Cf. A000010, A083254, A319340, A323911, A323912.

%K sign

%O 1,1

%A _Antti Karttunen_, Feb 12 2019