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%I #17 Jul 02 2022 16:14:00
%S 8,76,751,7508,75201,752451,7523259,75239327,752389040,7523761073,
%T 75238050781,752382051546,7523801085404,75237991990847,
%U 752380354682456,7523805396029055,75238037557271886
%N Number of deficient numbers < 10^n.
%C Limit_{n->oo} a(n)/10^n = 0.752... is the density of deficient numbers (A005100).
%t Accumulate@ Array[Count[Range[10^#, 10^(# + 1) - 1], _?(DivisorSigma[1, #] < 2 # &)] &, 6, 0] (* _Michael De Vlieger_, May 20 2018 *)
%o (GAP) P:=Filtered([1..10^7],n->Sigma(n)<2*n);;
%o o:=List([1..7],j->[]);; for i in [1..Length(P)] do for n in [1..Length(o)] do if P[i]<10^n then Add(o[n],P[i]); fi; od; od;
%o a:=List(o,Length);
%o (PARI) a(n) = sum(k=1, 10^n-1, sigma(k) < 2*k); \\ _Michel Marcus_, May 19 2018
%Y Cf. A005100, A302992.
%K nonn,more
%O 1,1
%A _Muniru A Asiru_, May 19 2018
%E a(11)-a(17) from _Hiroaki Yamanouchi_, Aug 03 2018
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