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 A321511 Number of alternating sign n X n matrices excluding permutation matrices. 1
 0, 0, 0, 1, 18, 309, 6716, 213308, 10809896, 911472580, 129530643900, 31095704935575, 12611311380675900, 8639383512070631700, 9995541355360989190800, 19529076234659969430529200, 64427185703425668434106855840, 358869201916137601091798728321296 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,5 LINKS Michael De Vlieger, Table of n, a(n) for n = 0..93 Paul Barry, Centered polygon numbers, heptagons and nonagons, and the Robbins numbers, arXiv:2104.01644 [math.CO], 2021. FORMULA a(n) = A005130(n) - n! MATHEMATICA a[n_] := Product[(3 k + 1)!/(n + k)!, {k, 0, n-1}] - n!; a /@ Range[0, 17] (* Giovanni Resta, Nov 20 2018 *) CROSSREFS Cf. A005130. Sequence in context: A091045 A179121 A226298 * A208537 A292299 A158532 Adjacent sequences: A321508 A321509 A321510 * A321512 A321513 A321514 KEYWORD nonn AUTHOR Wendy Appleby, Nov 11 2018 STATUS approved

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Last modified February 4 04:05 EST 2023. Contains 360045 sequences. (Running on oeis4.)