id:A059487 - OEIS Search Results

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Number of 2-enumeration of 4n X 4n quarter-turn symmetric alternating-sign matrices.

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1

1, 2, 80, 53760, 590413824, 104981650735104, 300931721514121691136, 13874404129378738693891686400, 10274196157891080769280680484929536000, 122089077024940067215877965611538507917950976000, 23266604385482749027479729551862778584550130343015874560000 (list; graph; listen)

	OFFSET	`0,2`
	LINKS	`G. Kuperberg, Symmetry classes of alternating-sign matrices under one roof, arXiv math.CO/0008184 [Th. 3]`
	MAPLE	`A059487 := proc(n) local i, j, t1; t1 := (-1)^(n(n-1)/2)2^(2n^2-n); for i to n do for j to n do t1 := t1(4j - 4i + 1)/(j - i + n); end do end do; t1 end proc;`
	CROSSREFS	`Sequence in context: A073499 A123828 A008563 this_sequence A056972 A051391 A041799` `Adjacent sequences: A059484 A059485 A059486 this_sequence A059488 A059489 A059490`
	KEYWORD	`nonn,easy`
	AUTHOR	`njas, Feb 04 2001`

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Last modified July 4 18:25 EDT 2008. Contains 140886 sequences.

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