[seqfan] Re: Hadamard matrices of small order and Yang conjecture

Joerg Arndt arndt at jjj.de
Fri Jan 1 22:59:42 CET 2010


Link for convenience:
  http://arxiv.org/abs/0912.5091

* Jonathan Post <jvospost3 at gmail.com> [Jan 02. 2010 08:35]:
> 191, 5767, 7081, 8249
> 
> Actually, several sequences here, and/or corrections tol old seqs?
> 
>  arXiv:0912.5091 [ps, pdf, other]
>     Title: Hadamard matrices of small order and Yang conjecture
>     Authors: Dragomir Z. Djokovic
>     Comments: 6 pages, 1 table
>     Subjects: Combinatorics (math.CO)
> 
>     We show that 138 odd values of n less than 10000 for which one
> knows how to construct a Hadamard matrix of order 4n have been
> overlooked in the recent handbook of combinatorial designs. There are
> four additional odd n, namely 191, 5767, 7081 and 8249, in that range
> for which we can construct a Hadamard matrix of order 4n. Our
> exhaustive computer searches show that the near-normal sequences NN(n)
> exist for n=36,38,40. Thus the Yang conjecture on the existence of
> NN(n) for all even n has been verified for n <= 40 but it still
> remains open.
> 
> Dec 27, 2009




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