|
%I #23 Oct 28 2018 08:46:05
%S 4,3,2,12,10,8,4,2,7,56,78,8,2,2,32,16,4,2,532,152,136,8,68,31,992,
%T 128,8,64,32,16,4,8,128,32,8,2,43648,2528,32,4,2,32,2272,32,32,127,
%U 16256,32,32,4,536,8,32,8,52,16,32,41044,64,512,128,64,16,4,2,8
%N Abundance of A181595(n).
%C a(n) is a proper divisor of A181595(n).
%H Michel Marcus, <a href="/A181596/b181596.txt">Table of n, a(n) for n = 1..200</a>
%H Paul Pollack and Vladimir Shevelev, <a href="https://doi.org/10.1016/j.jnt.2012.06.008">On perfect and near-perfect numbers</a>, J. Number Theory 132 (2012), pp. 3037-3046. <a href="http://arxiv.org/abs/1011.6160">arXiv:1011.6160</a>
%F a(n) = A033880(A181595(n)).
%e Since A181595(1)=12, a(1)=sigma(12)-2*12=28-24=4.
%t Reap[For[n = 12, n <= 2 10^7, n++, abn = DivisorSigma[1, n] - 2n; If[1 < abn < n && Divisible[n, abn], Print[{n, abn}]; Sow[abn]]]][[2, 1]] (* _Jean-François Alcover_, Oct 28 2018 *)
%Y Cf. A181595, A000396, A005101, A153501, A005820.
%K nonn
%O 1,1
%A _Vladimir Shevelev_, Nov 01 2010
%E a(10)-a(11) corrected by _Vladimir Shevelev_, Nov 03 2010
%E Entries checked, definition shortened by _R. J. Mathar_, Nov 17 2010
%E More terms from _Michel Marcus_, Feb 06 2016
|
