|
Search: id:A032260
|
|
|
| A032260 |
|
Number of n X n (0,1) matrices such that each row and each column is nondecreasing or nonincreasing. |
|
+0
4
|
|
| 2, 16, 102, 528, 2470, 11016, 47950, 205792, 874998, 3694920, 15519262, 64899456, 270415262
(list; graph; listen)
|
|
|
OFFSET
|
1,1
|
|
|
LINKS
|
Don Coppersmith, Ponder This: IBM Research Monthly Puzzles, March challenge
|
|
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
|
|
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: A005058 A082639 A043016 this_sequence A059204 A009619 A012024
Adjacent sequences: A032257 A032258 A032259 this_sequence A032261 A032262 A032263
|
|
KEYWORD
|
nonn
|
|
AUTHOR
|
Yuval Dekel (dekelyuval(AT)hotmail.com), Jun 25 2003
|
|
EXTENSIONS
|
Extended by Vladimir Baltic and Vladeta Jovovic (vladeta(AT)eunet.rs), Jul 10 2003
|
|
|
Search completed in 0.002 seconds
|
