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A035930 Maximal product of any two numbers whose concatenation is n. 12
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 0, 2, 4, 6, 8, 10, 12, 14, 16, 18, 0, 3, 6, 9, 12, 15, 18, 21, 24, 27, 0, 4, 8, 12, 16, 20, 24, 28, 32, 36, 0, 5, 10, 15, 20, 25, 30, 35, 40, 45, 0, 6, 12, 18, 24, 30, 36, 42, 48, 54, 0, 7, 14, 21, 28, 35, 42, 49, 56, 63, 0, 8, 16, 24, 32, 40, 48, 56, 64, 72, 0, 9, 18, 27, 36, 45, 54, 63, 72, 81, 0, 10, 20, 30, 40, 50, 60, 70 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,13

LINKS

Alois P. Heinz, Table of n, a(n) for n = 0..9999

EXAMPLE

a(341) = max(34*1,3*41) = 123.

MAPLE

a:= proc(n) local l, m; l:= convert(n, base, 10); m:= nops(l);

      `if`(m<2, 0, max(seq(parse(cat(seq(l[m-i], i=0..j-1)))

       *parse(cat(seq(l[m-i], i=j..m-1))), j=1..m)))

    end:

seq(a(n), n=0..120);  # Alois P. Heinz, May 22 2009

MATHEMATICA

Flatten[With[{c=Range[0, 9]}, Table[c*n, {n, 0, 10}]]] (* Harvey P. Dale, Jun 07 2012 *)

PROG

(Haskell)

a035930 n | n < 10    = 0

          | otherwise = maximum $ zipWith (*)

            (map read $ init $ tail $ inits $ show n)

            (map read $ tail $ init $ tails $ show n)

-- Reinhard Zumkeller, Aug 14 2011

CROSSREFS

Different from A007954. Cf. A035931-A035935.

Sequence in context: A080464 A171765 A257297 * A088117 A195833 A257294

Adjacent sequences:  A035927 A035928 A035929 * A035931 A035932 A035933

KEYWORD

nonn,base,nice,look

AUTHOR

Erich Friedman

EXTENSIONS

An erroneous formula was deleted by N. J. A. Sloane, Dec 23 2008

STATUS

approved

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Last modified July 28 19:33 EDT 2021. Contains 346335 sequences. (Running on oeis4.)