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%I #23 Apr 28 2021 10:11:08
%S 4,8,9,16,25,27,32,44,45,49,50,52,63,64,68,75,76,81,92,98,99,116,117,
%T 121,124,125,128,135,136,147,148,152,153,164,169,171,172,175,184,188,
%U 189,207,212,225,232,236,242,243,244,245,248,250,256,261,268,275,279
%N Nonsquarefree deficient numbers.
%H Michael De Vlieger, <a href="/A087244/b087244.txt">Table of n, a(n) for n = 1..10000</a>
%e m = 45 - 3*3*5 and sigma(45) = 78 < 2m = 90.
%t Select[Range@ 280, And[! SquareFreeQ@ #, DivisorSigma[1, #] < 2 #] &] (* _Michael De Vlieger_, Mar 25 2017 *)
%o (PARI) isok(n) = !issquarefree(n) && (sigma(n) < 2*n); \\ _Michel Marcus_, Dec 18 2013
%o (Python)
%o from sympy import divisor_sigma
%o from sympy.ntheory.factor_ import core
%o print([n for n in range(1,301) if core(n) != n and divisor_sigma(n)<2*n]) # _Indranil Ghosh_, Mar 26 2017
%Y Cf. A087245, A087246, A087247, A008683, A000203, A013929, A005117, A005100, A005101.
%K nonn
%O 1,1
%A _Labos Elemer_, Sep 05 2003
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