[seqfan] Re: No. of sign-nonsingular matrices

Eric W. Weisstein eww at wolfram.com
Fri Mar 27 03:34:21 CET 2009


On Thu, 26 Mar 2009, N. J. A. Sloane wrote:

> Eric,  doesn't  A = [-1]  also work?
>
> For then |A| = [1], per |A| = 1 = |det A|, so a(1) = 3 not 2 ?

Sorry, Neil.  I misread your "| det A |" as |A| == det A.

That changes the counts to

3, 73, 12787, ...

(Which also does not appear to be in OEIS).
-E




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