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A072504 a(n) = LCM of divisors of n which are <= sqrt(n).

%I A072504 #14 Mar 18 2018 04:05:40
%S A072504 1,1,1,2,1,2,1,2,3,2,1,6,1,2,3,4,1,6,1,4,3,2,1,12,5,2,3,4,1,30,1,4,3,
%T A072504 2,5,12,1,2,3,20,1,6,1,4,15,2,1,12,7,10,3,4,1,6,5,28,3,2,1,60,1,2,21,
%U A072504 8,5,6,1,4,3,70,1,24,1,2,15,4,7,6,1,40,9,2,1,84,5,2,3,8,1,90,7,4,3,2,5,24
%N A072504 a(n) = LCM of divisors of n which are <= sqrt(n).
%H A072504 Reinhard Zumkeller, <a href="/A072504/b072504.txt">Table of n, a(n) for n = 1..10000</a>
%e A072504 a(20) = 4: the divisors of 20 are 1,2,4,5,10 and 20; a(20) = lcm(1,2,4) = 4.
%p A072504 A072504 := proc(n)
%p A072504     local ds ;
%p A072504     ds := [] ;
%p A072504     for d in numtheory[divisors](n) do
%p A072504         if d^2 <= n then
%p A072504             ds := [op(ds),d] ;
%p A072504         end if;
%p A072504     end do:
%p A072504     ilcm(op(ds)) ;
%p A072504 end proc:
%p A072504 seq(A072504(n),n=1..20) ; # _R. J. Mathar_, Oct 03 2014
%t A072504 Table[LCM@@Select[Divisors[n],#<=Sqrt[n]&],{n,100}] (* _Harvey P. Dale_, Aug 26 2014 *)
%o A072504 (Haskell)
%o A072504 a072504 = foldl1 lcm . a161906_row  -- _Reinhard Zumkeller_, Mar 08 2013
%Y A072504 Cf. A072505.
%Y A072504 Cf. A161906, A072499.
%K A072504 nonn
%O A072504 1,4
%A A072504 _Amarnath Murthy_, Jul 20 2002
%E A072504 More terms from _Matthew Conroy_, Sep 09 2002