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%I #13 Jul 17 2023 00:59:20
%S 4,18,32,91,76,358,148,917,796,2368,408,10354,612,16586,16984,52873,
%T 1208,180408,1616,374934,271408,749070,2692,3350370,178376,4592968,
%U 4349008,13197802,5076,45402484,6108,74470417,64515400,149432876,10324768,652324677,10028
%N Expansion of Sum_{k>0} (1/(1 - k*x^k)^4 - 1).
%F a(n) = Sum_{d|n} (n/d)^d * binomial(d+3,3).
%t a[n_] := DivisorSum[n, (n/#)^# * Binomial[# + 3, 3] &]; Array[a, 40] (* _Amiram Eldar_, Jul 17 2023 *)
%o (PARI) a(n) = sumdiv(n, d, (n/d)^d*binomial(d+3, 3));
%Y Cf. A338662, A362683, A363639.
%Y Cf. A116963, A363648.
%K nonn
%O 1,1
%A _Seiichi Manyama_, Jun 13 2023