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a(n) is the largest 5-digit number with exactly n divisors, or a(n) = 0 if no such number exists.
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%I #11 Nov 07 2020 11:23:50

%S 0,99991,97969,99998,83521,99997,15625,99995,98596,99952,59049,99999,

%T 0,99873,99856,99992,65536,99972,0,99984,88209,99328,0,99996,50625,

%U 94208,96100,99904,0,99568,0,99968,50176,0,40000,99936,0,0,36864,99760,0,99648,0

%N a(n) is the largest 5-digit number with exactly n divisors, or a(n) = 0 if no such number exists.

%H Jinyuan Wang, <a href="/A182698/b182698.txt">Table of n, a(n) for n = 1..128</a>

%F A000005(a(n)) = n for a(n) > 0.

%F 128 = max n such that a(n) > 0, a(n) = 0 for n > 128.

%F a(n) >= A182697(n).

%t With[{nd=Table[{n,DivisorSigma[0,n]},{n,99999,10000,-1}]},Table[ SelectFirst[ nd,#[[2]]==k&],{k,50}]][[All,1]]/."NotFound"->0 (* Requires Mathematica version 10 or later *) (* _Harvey P. Dale_, Mar 13 2018 *)

%Y Cf. A182697.

%K nonn,base

%O 1,2

%A _Jaroslav Krizek_, Nov 27 2010