

A057144


Smallest of the most frequently occurring numbers in 1ton multiplication table.


10



1, 2, 2, 4, 4, 6, 6, 6, 6, 6, 6, 12, 12, 12, 12, 12, 12, 36, 36, 60, 60, 60, 60, 24, 24, 24, 24, 24, 24, 60, 60, 60, 60, 60, 60, 60, 60, 60, 60, 120, 120, 120, 120, 120, 120, 120, 120, 120, 120, 120, 120, 120, 120, 120, 120, 120, 120, 120, 120, 120, 120, 120, 120, 120
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OFFSET

1,2


LINKS

Reinhard Zumkeller, Table of n, a(n) for n = 1..1000
Benjamin Dickman, What number appears most often in an n X n multiplication table?, Mathematics StackExchange, May 2014.


EXAMPLE

M(n) is the array in which m(x,y)= x*y for x = 1 to n and y = 1 to n. In m(10), the most frequently occurring numbers are 6, 8, 10, 12, 18, 20, 24, 30,40, each occurring 4 times. The smallest of these numbers is 6, so a(10) = 6.


PROG

(Haskell)
import Data.List (sort, group, sortBy, groupBy)
import Data.Function (on)
a057144 n = head $ last $ head $ groupBy ((==) `on` length) $
reverse $ sortBy (compare `on` length) $
group $ sort [u * v  u < [1..n], v < [1..n]]
 Reinhard Zumkeller, Jun 22 2013


CROSSREFS

Cf. A057142, A057143, A057338.
Sequence in context: A007730 A330271 A257686 * A198332 A080606 A083535
Adjacent sequences: A057141 A057142 A057143 * A057145 A057146 A057147


KEYWORD

nonn


AUTHOR

Arran Fernandez, Aug 13 2000


EXTENSIONS

More terms from Larry Reeves (larryr(AT)acm.org), Apr 18 2001


STATUS

approved



