A140954 - OEIS

A140954

Half the number of n X n binary matrices, symmetric under vertical reflection, having equal row sums.

%I #7 Mar 09 2015 04:30:46

%S 1,2,10,35,1126,7592,1697508,22458249,36000614026,941605438142,

%T 11035829403860196,572800408273738658,49759074151291691916640,

%U 5136409738603278958315040,3340664790391139471267200338312

%N Half the number of n X n binary matrices, symmetric under vertical reflection, having equal row sums.

%H R. H. Hardin, Jul 28 2008, <a href="/A140954/b140954.txt">Table of n, a(n) for n = 1..25</a>

%K nonn

%O 1,2

%A _R. H. Hardin_, Jul 28 2008