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A059436 Smallest number whose set of divisors contains each digit 0-9 at least n times. 7
108, 540, 1140, 1890, 3420, 5460, 7980, 11760, 16380, 23520, 23520, 23760, 38220, 38220, 41580, 41580, 41580, 71820, 71820, 71820, 83160, 83160, 83160, 124740, 124740, 143640, 166320, 166320, 249480, 249480, 249480, 249480, 311220, 335160, 415800, 415800, 415800, 415800, 415800, 415800 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,1
LINKS
Erich Friedman, What's Special About This Number? (See entry 7980.)
EXAMPLE
The divisors of 540 are 1, 2, 3, 4, 5, 6, 9, 10, 12, 15, 18, 20, 27, 30, 36, 45, 54, 60, 90, 108, 135, 180, 270, 540 and every digit appears at least twice in this list.
MATHEMATICA
T = 0*Range[25]; Do[d = Last /@ Tally@ Flatten[ IntegerDigits /@ Divisors@ n]; If[Length@d == 10, m = Min[25, d]; While[m > 0 && (T[[m]] == 0 || n < T[[m]]), T[[m--]] = n]], {n, 125000}]; T (* Giovanni Resta, May 15 2016 *)
sded[n_]:=With[{fid=Flatten[IntegerDigits/@Divisors[n]]}, If[Length[Union[fid]]==10, {n, Min[ Tally[fid][[;; , 2]]]}, Nothing]]; Table[SelectFirst[sded/@Range[500000], #[[2]]>k&], {k, 0, 39}][[;; , 1]] (* Harvey P. Dale, Mar 27 2024 *)
PROG
(Haskell)
import Data.List (group, sort)
a059436 n = head [x | x <- [1..],
let dds = map length $ group $ sort $ concatMap show $ a027750_row x,
minimum dds == n, length dds == 10]
-- Reinhard Zumkeller, Feb 04 2012
CROSSREFS
Cf. A027750; subsequence of A095050, A095048.
Sequence in context: A251270 A255083 A063880 * A233685 A160919 A129027
KEYWORD
base,nonn,nice
AUTHOR
Erich Friedman, Feb 01 2001
EXTENSIONS
More terms from David W. Wilson, Aug 31 2001
Offset corrected by R. J. Mathar, Jun 02 2010
a(10)-a(36) corrected by Giovanni Resta, May 15 2016
More terms from Harvey P. Dale, Mar 27 2024
STATUS
approved

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Last modified July 15 16:08 EDT 2024. Contains 374333 sequences. (Running on oeis4.)