A145777 - OEIS

A145777

Number of n X n binary arrays symmetric about both diagonal and antidiagonal with all ones connected only either two adjacent vertically or two adjacent horizontally.

%I #3 Mar 31 2012 12:35:08

%S 1,1,1,2,4,7,20,66,223,972,5286,31417,228724,2000916,20634823,

%T 248726975,3651917796,62467383723,1283523230287,30987743547862,

%U 900690199090722,30606347558434592,1253939853475088497,60154380091248350142

%N Number of n X n binary arrays symmetric about both diagonal and antidiagonal with all ones connected only either two adjacent vertically or two adjacent horizontally.

%K nonn

%O 1,4

%A _R. H. Hardin_, Oct 18 2008