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Product of divisors of n which are >= n^(1/2).
16

%I #5 Dec 05 2013 19:55:21

%S 1,2,3,8,5,18,7,32,27,50,11,288,13,98,75,512,17,972,19,1000,147,242,

%T 23,13824,125,338,243,2744,29,27000,31,4096,363,578,245,419904,37,722,

%U 507,64000,41,86436,43,10648,6075,1058,47,1769472,343,12500,867,17576,53

%N Product of divisors of n which are >= n^(1/2).

%C a(n) = n iff n is not a composite number.

%H Harvey P. Dale, <a href="/A072500/b072500.txt">Table of n, a(n) for n = 1..1000</a>

%e The divisors of 20 are 1, 2, 4, 5, 10 and 20. a(20) = 5*10*20= 1000.

%t Table[Times @@ Select[Divisors[n], # >= Sqrt[n] &], {n, 1, 55}]

%Y Cf. A072499, A072501 & A070038.

%K nonn

%O 1,2

%A _Amarnath Murthy_, Jul 20 2002

%E Edited by _Robert G. Wilson v_, Jul 22 2002

%E Corrected a(16) by Harvey P. Dale, Oct 06 2011