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%I #7 Apr 04 2020 10:33:24
%S 1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,5,1,1,1,5,1,1,1,5,1,1,1,5,1,1,1,5,1,1,
%T 1,11,1,1,1,5,1,7,1,5,1,1,1,11,1,1,1,5,1,7,1,5,1,1,1,11,1,1,1,13,1,7,
%U 1,5,1,1,1,19,1,1,1,5,1,7,1,13,10,1,1,11,1,1,1,13,1,16
%N Sum of nonprime divisors of n that are <= sqrt(n).
%F G.f.: Sum_{k>=1} A018252(k) * x^(A018252(k)^2) / (1 - x^A018252(k)).
%t Table[DivisorSum[n, # &, # <= Sqrt[n] && !PrimeQ[#] &], {n, 1, 90}]
%t nmax = 90; CoefficientList[Series[Sum[Boole[!PrimeQ[k]] k x^(k^2)/(1 - x^k), {k, 1, nmax}], {x, 0, nmax}], x] // Rest
%o (PARI) a(n) = sumdiv(n, d, if ((d^2<=n) && !isprime(d), d)); \\ _Michel Marcus_, Apr 03 2020
%Y Cf. A018252, A023890, A066839, A069289, A069293, A097974, A333748, A333752, A333753.
%K nonn
%O 1,16
%A _Ilya Gutkovskiy_, Apr 03 2020
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