login
The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
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: A076615 A098777 A127226 * A216387 A062282 A230990

Adjacent sequences:  A001116 A001117 A001118 * A001120 A001121 A001122

KEYWORD

nonn,hard,more,nice

AUTHOR

N. J. A. Sloane.

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
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified April 18 21:37 EDT 2021. Contains 343089 sequences. (Running on oeis4.)