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%I #15 Mar 16 2019 16:09:00
%S 172622505,6217560734,16017860054,18102483014,20021589510,31285993970,
%T 32576024810,39270110990,68700877014,80170395410,81142298930,
%U 99542647490,125182657005,144194617490,153113328654,181335043274,318710758730,374642686418,378482712530,455440763414
%N Lesser of reduced unitary amicable pair.
%C A pair m < n is a reduced unitary amicable pair if usigma(m) = usigma(n) = m + n + 1, where usigma(n) is the sum of unitary divisors of n (A034460).
%C The larger members are in A306876.
%H Amiram Eldar, <a href="/A306875/b306875.txt">Table of n, a(n) for n = 1..28</a> (terms below 10^12, from David Moews's site).
%H David Moews, <a href="http://djm.cc/amicable.html">Perfect, amicable and sociable numbers</a>
%H J. O. M. Pedersen, <a href="http://62.198.248.44/aliquot/tables.htm">Tables of Aliquot Cycles</a>
%e 172622505 is in the sequence since it is the lesser of the amicable pair (172622505, 175742294): usigma(172622505) = usigma(175742294) = 348364800 = 172622505 + 175742294 + 1.
%t us[n_] := Times @@ (1 + Power @@@ FactorInteger[n]) - n; s={}; Do[m = us[n] - 1; If[m > n && us[m] == n + 1, AppendTo[s, n]], {n, 1, 10^9}]; s
%Y Cf. A003502, A002952, A126172, A034460, A306876.
%K nonn
%O 1,1
%A _Amiram Eldar_, Mar 14 2019
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