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%I #17 Sep 06 2022 10:24:13
%S 1,4,7,8,12,14,15,24,28,32,39,42,56,60,63,72,80,84,90,91,96,104,112,
%T 114,120,124,126,128,133,160,168,171,186,195,210,216,224,234,240,248,
%U 252,255,256,260,280,288,294,300,308,312,336,360,363,372,378,384,392
%N Numbers k such that the equation sigma(sigma(x)) = k has solutions.
%C Complement of A162923. - _Jaroslav Krizek_, Jul 19 2009
%H Ivan Neretin, <a href="/A070286/b070286.txt">Table of n, a(n) for n = 1..10000</a>
%t mx = 400; Select[Union@Table[Nest[DivisorSigma[1, #] &, n, 2], {n, mx}], # < mx &] (* _Ivan Neretin_, Feb 12 2018 *)
%Y Cf. A162923.
%K easy,nonn
%O 1,2
%A _Benoit Cloitre_, May 10 2002
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