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A182694 a(n) = the largest 3-digit number with exactly n divisors, a(n) = 0 if no such number exists. 1
0, 997, 961, 998, 625, 981, 729, 999, 676, 976, 0, 996, 0, 832, 784, 984, 0, 980, 0, 912, 576, 0, 0, 990, 0, 0, 900, 960, 0, 720, 0, 840, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

max {n : a(n) > 0} = 32, a(n) = 0 for n > 32.

LINKS

Table of n, a(n) for n=1..53.

FORMULA

a(n) = max {99 < k < 1000 : A000005(k)=n} if set is nonempty, else a(n) = 0.

MAPLE

with (numtheory):

b:= n-> `if` (type (n, integer), n, 0):

a:= n-> b (max (select (x-> tau(x)=n, [$100..999])[])):

seq (a(n), n=1..60);

MATHEMATICA

digits=3; tbl=DivisorSigma[0, Range[10^(digits-1), 10^digits-1]]; t=Table[0, {Max[tbl]}]; offset=10^(digits-1)-1; Do[t[[tbl[[i]]]]=i+offset, {i, Length[tbl]}]; t

(With[{tb=Table[{n, DivisorSigma[0, n]}, {n, 999, 100, -1}]}, Table[SelectFirst[ tb, #[[2]]==k&], {k, 60}]]/.Missing["NotFound"]->{0, 0})[[All, 1]] (* Requires Mathematica version 10 or later *) (* Harvey P. Dale, Nov 02 2019 *)

CROSSREFS

Cf. A000005, A182693.

Sequence in context: A028513 A267119 A210315 * A234847 A057698 A106763

Adjacent sequences:  A182691 A182692 A182693 * A182695 A182696 A182697

KEYWORD

nonn,base

AUTHOR

Jaroslav Krizek, Nov 27 2010

EXTENSIONS

Edited by Alois P. Heinz, Nov 27 2010

STATUS

approved

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Last modified September 22 22:24 EDT 2020. Contains 337291 sequences. (Running on oeis4.)