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%I #13 Oct 27 2023 22:00:46
%S 6,9,10,15,16,20,21,22,25,28,30,33,34,36,39,42,44,45,46,48,49,50,51,
%T 54,55,57,58,60,64,68,69,70,72,75,76,78,80,81,82,84,85,87,91,93,94,96,
%U 98,99,100,102,105,106,108,111,114,115,116,117,118,120,121,123,124,126
%N Chowla's function of n is not divisible by the number of proper divisors of n.
%C Chowla's function (A048050) = sum of divisors of n except 1 and n.
%H Amiram Eldar, <a href="/A054020/b054020.txt">Table of n, a(n) for n = 1..10000</a>
%p with(numtheory):
%p [seq(`if`((sigma(i)-i-1) mod (tau(i)-1) <> 0,i,print( )),i=2..500)];
%t Select[Range[2,150],!Divisible[DivisorSigma[1,#]-#-1,DivisorSigma[ 0,#]- 1]&] (* _Harvey P. Dale_, May 27 2014 *)
%Y Complement is A054021.
%Y Cf. A032741, A048050, A054015.
%K nonn
%O 1,1
%A _Asher Auel_, Jan 19 2000
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