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A180512
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Triangle of the number of alternating sign matrices according to the number of -1's
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0
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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, 326, 26, 1
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OFFSET
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1,2
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COMMENTS
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The first column is the factorial, A000142.
The second column forms coefficients of Laguerre polynomials, A001810.
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LINKS
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Table of n, a(n) for n=1..29.
Wikipedia, Alternating Sign Matrix
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EXAMPLE
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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=7:5040,29400,63308,66158,38390,13037,2660,326,26,1
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CROSSREFS
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Sequence in context: A181299 A181365 A221913 * A132181 A027642 A117214
Adjacent sequences: A180509 A180510 A180511 * A180513 A180514 A180515
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KEYWORD
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nonn,hard
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AUTHOR
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Arvind Ayyer, Jan 20 2011
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STATUS
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approved
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