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%I #12 Sep 07 2019 08:49:25
%S 2,6,8,3,10,144,14,15,64,324,400,21,22,13824,5,26,27,784,27000,1024,
%T 33,34,35,279936,38,39,64000,74088,1936,2025,46,5308416,7,2500,51,
%U 2704,157464,55,175616,57,58,777600000,62,3969,32768,65,287496,4624,69
%N Product of aliquot divisors of composite n (1 and primes omitted).
%D Albert H. Beiler, Recreations in the Theory of Numbers, 2nd ed., pages 10, 23. New York: Dover, 1966. ISBN 0-486-21096-0.
%H Amiram Eldar, <a href="/A048741/b048741.txt">Table of n, a(n) for n = 1..10000</a>
%F a(n) = A007956(A002808(n)). - _Michel Marcus_, Sep 07 2019
%e The third composite number is 8, for which the product of aliquot divisors is 4*2*1 = 8, so a(3)=8.
%t Composite[n_] := FixedPoint[n + PrimePi[ # ] + 1 &, n + PrimePi[n] + 1]; Table[ Times @@ Select[ Divisors[ Composite[n]], # < Composite[n] & ], {n, 1, 60} ]
%t pd[n_] := n^(DivisorSigma[0, n]/2 - 1); pd /@ Select[Range[100], CompositeQ] (* _Amiram Eldar_, Sep 07 2019 *)
%Y This is A007956 omitting the 1's.
%Y Cf. A002808, A007422, A007956, A048740.
%K easy,nonn
%O 1,1
%A _Enoch Haga_
%E a(33) inserted by _Amiram Eldar_, Sep 07 2019
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