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A001119 Number of skew-symmetric Hadamard matrices of order 4n. 0
1, 1, 2, 2, 16, 54 (list; graph; refs; listen; history; text; internal format)
OFFSET
2,3
LINKS
Table of n, a(n) for n=2..7.
F. J. Aragon Artacho, J. M. Borwein, M. K. Tam, Douglas-Rachford Feasibility Methods for Matrix Completion Problems, March 2014.
J. Gebel, Integer points on Mordell curves [Cached copy, after the original web site tnt.math.se.tmu.ac.jp was shut down in 2017]
C. Koukouvinos and S. Stylianou, On skew-Hadamard matrices, Discrete Math., 308 (2008), 2723-2731.
Edward Spence, Classification of Hadamard matrices of order 24 and 28, Discrete Math. 140 (1995), no. 1-3, 185-243.
CROSSREFS
Sequence in context: A098777 A127226 A371548 * A216387 A062282 A230990
Adjacent sequences: A001116 A001117 A001118 * A001120 A001121 A001122
KEYWORD
nonn,hard,more,nice
AUTHOR
N. J. A. Sloane.
STATUS
approved

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Last modified September 6 12:50 EDT 2024. Contains 375712 sequences. (Running on oeis4.)