login
This site is supported by donations to The OEIS Foundation.

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A180512 Triangle of the number of alternating sign matrices according to the number of -1's 0
1, 2, 6, 1, 24, 16, 2, 120, 200, 94, 14, 1, 720, 2400, 2684, 1284, 310, 36, 2, 5040, 29400, 63308, 66158, 38390, 13037, 2660, 328, 26, 1 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

The first column is the factorial, A000142.

The second column forms coefficients of Laguerre polynomials, A001810.

From Arvind Ayyer, Mar 15 2018: (Start)

Consider the row generating function A_n(x) = sum_k a(n,k) x^k. Then

A_n(0) = n!, A000142.

A_n(1) = number of ASM's, A005130.

A_n(2) = number of domino tilings of the Aztec diamond, A006125.

A_n(3) = 3-enumeration of n X n alternating-sign matrices, A059477. (End)

LINKS

Table of n, a(n) for n=1..29.

FindStat - Combinatorial Statistic Finder, The number of entries equal to negative one in the alternating sign matrix

Florent Le Gac, Quelques problèmes d’énumération autour des matrices à signes alternants, thesis, LaBRI Bordeaux, 2011.

Wikipedia, Alternating Sign Matrix

EXAMPLE

In triangular format, the numbers of ASMs is as follows:

n=1:1

n=2:2

n=3:6,1

n=4:24,16,2

n=5:120,200,94,14,1

n=6:720,2400,2684,1284,310,36,2

n=7:5040,29400,63308,66158,38390,13037,2660,328,26,1

CROSSREFS

Row sums are A005130

Cf. A000142, A006125, A059477, A001810.

Sequence in context: A281046 A281521 A281635 * A132181 A291646 A027642

Adjacent sequences:  A180509 A180510 A180511 * A180513 A180514 A180515

KEYWORD

nonn,hard,tabf

AUTHOR

Arvind Ayyer, Jan 20 2011

EXTENSIONS

T(7, 7) corrected by Arvind Ayyer, Feb 12 2018

STATUS

approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent | More pages
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy .

Last modified August 14 06:01 EDT 2018. Contains 313748 sequences. (Running on oeis4.)