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%I #32 Mar 06 2020 22:58:10
%S 2,4,8,9,10,12,16,18,24,25,26,28,32,34,36,40,48,50,52,58,63,64,72,74,
%T 75,76,80,81,82,84,88,90,98,100,104,106,108,112,117,120,121,122,124,
%U 128,130,136,144,146,148,152,156,160,162,170,171,172,175
%N Number of divisors of n does not divide sum of divisors of n.
%C A054025(a(n)) > 0. - _Reinhard Zumkeller_, Jan 06 2012
%C A245656(a(n)) = 0. - _Reinhard Zumkeller_, Jul 28 2014
%D Handbook of Number Theory, D. S. Mitrinovic et al., Kluwer, Section III.51.
%H Reinhard Zumkeller, <a href="/A049642/b049642.txt">Table of n, a(n) for n = 1..10000</a>
%H Wikipedia, <a href="http://en.wikipedia.org/wiki/Arithmetic_number">Arithmetic number</a>
%p isA049642 := proc(n)
%p if modp(numtheory[sigma](n),numtheory[tau](n)) = 0 then
%p false;
%p else
%p true;
%p end if;
%p end proc:
%p A049642 := proc(n)
%p option remember;
%p if n = 1 then
%p 2;
%p else
%p for a from procname(n-1)+1 do
%p if isA049642(a) then
%p return a;
%p end if;
%p end do:
%p end if;
%p end proc: # _R. J. Mathar_, Oct 26 2015
%t Select[Range[175], Mod[DivisorSigma[1, #], DivisorSigma[0, #]] > 0 &] (* _Jayanta Basu_, Mar 28 2013 *)
%o (Haskell)
%o a049642 n = a049642_list !! (n-1)
%o a049642_list = filter ((== 0) . a245656) [1..]
%o -- _Reinhard Zumkeller_, Jan 06 2012
%o (GAP) a:=Filtered([1..180],n->Sigma(n) mod Tau(n)>0);; Print(a); # _Muniru A Asiru_, Jan 25 2019
%Y Complement of A003601.
%Y Cf. A000005, A000203.
%Y Cf. A245656.
%K nonn,easy
%O 1,1
%A _N. J. A. Sloane_
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