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A032260
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Number of n X n (0,1) matrices such that each row and each column is nondecreasing or nonincreasing.
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4
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2, 16, 102, 528, 2470, 11016, 47950, 205792, 874998, 3694920, 15519262, 64899456, 270415262
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,1
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LINKS
| Don Coppersmith, Ponder This: IBM Research Monthly Puzzles, March challenge
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FORMULA
| a(n) = 2*n*(binomial(2*n, n)-n). G.f.: 4*x/(1-4*x)^(3/2)-2*x*(1+x)/(1-x)^3. - Vladimir Baltic and Vladeta Jovovic (vladeta(AT)eunet.rs), Jul 10 2003
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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: A082639 A043016 A197202 * A197800 A059204 A187248
Adjacent sequences: A032257 A032258 A032259 * A032261 A032262 A032263
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KEYWORD
| nonn
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AUTHOR
| Yuval Dekel (dekelyuval(AT)hotmail.com), Jun 25 2003
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EXTENSIONS
| Extended by Vladimir Baltic and Vladeta Jovovic (vladeta(AT)eunet.rs), Jul 10 2003
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