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Expansion of Product_{k>=1} (1 - x^sigma(k)).
3

%I #19 Jun 01 2018 10:42:50

%S 1,-1,0,-1,0,1,-1,1,-1,2,1,0,-3,0,0,2,1,-2,0,1,2,-1,-3,-4,0,3,4,0,-4,

%T -1,6,-3,3,-9,0,5,10,0,-6,-7,0,6,-2,2,-9,6,7,4,-7,-7,-11,8,11,3,-5,-1,

%U -3,9,-10,1,-9,0,16,8,0,-4,-4,-20,12,-8,11,0,-7,14,-2

%N Expansion of Product_{k>=1} (1 - x^sigma(k)).

%H Seiichi Manyama, <a href="/A305320/b305320.txt">Table of n, a(n) for n = 0..1000</a>

%p with(numtheory):

%p seq(coeff(series(mul(1-x^sigma(k),k=1..n), x,90),x,n),n=0..80); # _Muniru A Asiru_, May 31 2018

%o (PARI) N=99; x='x+O('x^N); Vec(prod(k=1, N, 1-x^sigma(k)))

%Y Cf. A000203, A111865, A305321.

%K sign

%O 0,10

%A _Seiichi Manyama_, May 30 2018