A057143 Largest of the most frequently occurring numbers in 1-to-n multiplication table.

1, 2, 6, 4, 4, 12, 12, 24, 24, 40, 40, 24, 24, 24, 60, 60, 60, 36, 36, 60, 60, 60, 60, 120, 120, 120, 120, 168, 168, 120, 120, 120, 120, 120, 120, 180, 180, 180, 180, 120, 120, 120, 120, 120, 360, 360, 360, 360, 360, 360, 360, 360, 360, 360, 360, 360, 360, 360

Offset: 1

Author

Arran Fernandez, Aug 13 2000

Keywords

• nonn

Examples

			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 largest of these numbers is 40, so a(10) = 40.
		

Links

• Branden Aldridge, Table of n, a(n) for n = 1..20000 (first 1000 terms from Reinhard Zumkeller).

Crossrefs

Cf. A057142, A057144, A057338.

Programs

Haskell

import Data.List (group, sort, sortBy)
import Data.Function (on)
a057143 n = head $ head $ reverse $ sortBy (compare `on` length) $
            group $ sort [u * v | u <- [1..n], v <- [1..n]]
-- Reinhard Zumkeller, Jun 22 2013

Extensions

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