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%I #8 Mar 09 2016 17:30:34
%S 2,3,4,20,6,35,8,18,30,77,12,728,14,45,16,680,18,1881,20,252,110,299,
%T 24,3850,130,135,84,5104,30,75361,32,396,238,665,36,28860,38,273,80,
%U 82082,42,218569,44,360,2898,1175,48,193648,350,2295,260,25228,54,33495
%N Earliest sequence such that (x+y) | a(xy) for all x>=1, y>=1.
%H Alois P. Heinz, <a href="/A169901/b169901.txt">Table of n, a(n) for n = 1..20000</a>
%p a:= n-> ilcm(seq(d+n/d, d=numtheory[divisors](n))):
%p seq(a(n), n=1..60); # _Alois P. Heinz_, Mar 09 2016
%t eq[n_] := And @@ Table[y = n/x; Mod[a[x*y], x + y] == 0, {x, Divisors[n]}]; r[n_] := Reduce[ eq[n], a[n], Integers] /. C[1] -> 1; Table[a[n] /. ToRules[r[n]], {n, 1, 51}] (* _Jean-François Alcover_, Aug 03 2012 *)
%K nonn,nice
%O 1,1
%A _Andrew Weimholt_, Jul 05 2010
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