Sorry, Edwin did do the GF(2) version, which is now A225371 (and could use more terms). The real-valued (0,1} version - where it is a set not a ring - may or may not be in the OEIS. On Tue, May 7, 2013 at 2:37 PM, Neil Sloane <njasloane@gmail.com> wrote:
Edwin, Thanks, I will enter that sequence this afternoon.
I was wrong of course in calling it a ring (the result of too many years working in the "mod 2" world - and there the same sequence is also of interest but is probably in the OEIS already: number of nxn matrices over GF(2) that are squares). It is just a set.
On Tue, May 7, 2013 at 2:17 PM, W. Edwin Clark <wclark@mail.usf.edu> wrote:
Brute force gives the following for a(n) = number of squares in M(n,2) = ring of nxn matrices over GF(2), beginning with n = 1: 2,10,260,31096 which is not in the OEIS. Perhaps some interested soul can extend this.
On Tue, May 7, 2013 at 1:08 PM, Neil Sloane <njasloane@gmail.com> wrote:
That's related to several questions that have interested me for decades. Here's a simple version: choose your favorite matrix ring R, e.g. real matrices with entries that are 0 or 1. What is a(n) := number of nxn matrices in R that have a square root in R?
_______________________________________________
Seqfan Mailing list - http://list.seqfan.eu/
-- Dear Friends, I have now retired from AT&T. New coordinates:
Neil J. A. Sloane, President, OEIS Foundation 11 South Adelaide Avenue, Highland Park, NJ 08904, USA Phone: 732 828 6098; home page: http://NeilSloane.com Email: njasloane@gmail.com
-- Dear Friends, I have now retired from AT&T. New coordinates: Neil J. A. Sloane, President, OEIS Foundation 11 South Adelaide Avenue, Highland Park, NJ 08904, USA Phone: 732 828 6098; home page: http://NeilSloane.com Email: njasloane@gmail.com