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%I #16 Jul 19 2023 02:19:14
%S 1,4,7,17,16,55,29,129,100,311,67,1135,92,1919,1486,5409,154,17038,
%T 191,33491,20938,67871,277,262861,9701,373127,296110,978727,436,
%U 3134821,497,5051969,3898522,10027655,474146,39352069,704,49808159,48362926,127403221,862,411286429,947
%N Expansion of Sum_{k>0} x^k/(1 - k*x^k)^3.
%F a(n) = Sum_{d|n} (n/d)^(d-1) * binomial(d+1,2).
%t a[n_] := DivisorSum[n, (n/#)^(#-1) * Binomial[# + 1, 2] &]; Array[a, 50] (* _Amiram Eldar_, Jul 18 2023 *)
%o (PARI) a(n) = sumdiv(n, d, (n/d)^(d-1)*binomial(d+1, 2));
%Y Cf. A363639, A363643, A363644.
%Y Cf. A167531, A363645.
%Y Cf. A007437, A363650.
%K nonn
%O 1,2
%A _Seiichi Manyama_, Jun 13 2023
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