[seqfan] Re: How many ways to dissect a square into 4 congruent pieces

[Giovanni Resta]

On 05/13/2015 07:56 PM, Neil Sloane wrote:
> I have now updated the entry for A003213 with a copy of Tom Parkin's
> 11-page letter to Fred Gruenberger, giving more information about his
> calculations. I hope that this will explain why his results are different
> from Don's and Giovanni's.  In any case, could you (Giovanni, perhaps)
> create
> a new entry for your results (and tell me the A-number)?

Tomorrow I will read carefully those pages. Since I'm not generally
very self-confident, my first assumption was that my program was bugged
or that I understood the problem in a different way.

Anyway, in the meantime I've created a PDF with all the 596
rotationally symmetric quarterings of the 8x8 chessboard I found.

The 4-th page contains the 71  from-the-midpoint dissections Don Reble 
and I counted (Parkin counted 87 of them).

I'm not really good with shapes, but maybe somebody can
look at those 71 little squares and find a missing dissection.

Until I upload the picture to an appropriate sequence, it can be
seen here http://www.iread.it/quartering.pdf

Giovanni