

A032260


Number of n X n (0,1) matrices such that each row and each column is nondecreasing or nonincreasing.


5



2, 16, 102, 528, 2470, 11016, 47950, 205792, 874998, 3694920, 15519262, 64899456, 270415262, 1123264408, 4653525150, 19234571968, 79342610902, 326704870152, 1343120023678, 5513861152000, 22606830725598, 92580354402712, 378737813468542, 1547884976787648
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OFFSET

1,1


LINKS

Eric M. Schmidt, Table of n, a(n) for n = 1..1000
Don Coppersmith, Ponder This: IBM Research Monthly Puzzles, March challenge


FORMULA

a(n) = 2*n*(binomial(2*n, n)n). G.f.: 4*x/(14*x)^(3/2)2*x*(1+x)/(1x)^3.  Vladimir Baltic and Vladeta Jovovic, Jul 10 2003


CROSSREFS

The number of n X n 0, 1 matrices such that each row and each column is increasing is in sequence A000984.
Cf. A000984, A062528, A045992, A016742, A086113  A086115.
Sequence in context: A319603 A043016 A197202 * A197800 A209645 A207062
Adjacent sequences: A032257 A032258 A032259 * A032261 A032262 A032263


KEYWORD

nonn


AUTHOR

Yuval Dekel (dekelyuval(AT)hotmail.com), Jun 25 2003


EXTENSIONS

Extended by Vladimir Baltic and Vladeta Jovovic, Jul 10 2003
More terms from Eric M. Schmidt, May 01 2013


STATUS

approved



