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 A054010 Numbers n with property that n is divisible by the number of its proper divisors. 4

%I

%S 2,3,4,5,6,7,11,13,15,16,17,19,20,21,23,27,29,31,33,37,39,41,42,43,45,

%T 47,50,51,53,56,57,59,61,67,69,70,71,73,75,79,83,87,89,93,97,101,103,

%U 105,107,109,111,113,120,123,127,129,131,132,137,139,141,149,151,154

%N Numbers n with property that n is divisible by the number of its proper divisors.

%C All primes are in this sequence, having only one proper divisor. The specifically nonprime members of this sequence are in A055719. - _Carl R. White_, Jul 11 2012

%H Carl R. White, <a href="/A054010/b054010.txt">Table of n, a(n) for n = 1..10000</a>

%F Numbers n such that A054009(n) = 0.

%e There are three proper divisors of 6, {1, 2, 3}, 6 is divisible by 3.

%p [seq(`if`(i mod (tau(i)-1) = 0,i,print( )), i=2..190)];

%t Select[Range[2, 100], IntegerQ[ #/(-1+DivisorSigma[0, # ])]&] (* _Wouter Meeussen_, Jun 07 2005 *)

%Y Cf. A032741, A033950, A054009, A055719.

%K nonn

%O 1,1

%A Asher Auel (asher.auel(AT)reed.edu), Jan 12 2000

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Last modified October 22 08:00 EDT 2019. Contains 328315 sequences. (Running on oeis4.)