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Expansion of Product_{k>=1} (1 + x^sigma(k)) / (1 - x^sigma(k)).
0

%I #14 Mar 08 2020 10:15:52

%S 1,2,2,4,8,10,14,24,34,44,62,86,116,156,206,274,362,462,598,782,994,

%T 1258,1606,2018,2528,3178,3952,4904,6094,7490,9194,11322,13834,16836,

%U 20518,24880,30086,36366,43792,52656,63250,75626,90344,107926,128422,152546

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

%C Convolution of A111865 and A305321.

%t nmax = 50; CoefficientList[Series[Product[(1 + x^DivisorSigma[1, k])/(1 - x^DivisorSigma[1, k]), {k, 1, nmax}], {x, 0, nmax}], x]

%Y Cf. A000203, A111865, A305321.

%K nonn

%O 0,2

%A _Vaclav Kotesovec_, Mar 06 2020