A145814 - OEIS

A145814

1/4 of the number of islands of ones fitting in an n X n array symmetric about both diagonal and antidiagonal with all ones connected only either three adjacent vertically or three adjacent horizontally.

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

%S 0,0,0,0,1,1,1,1,3,3,4,4,6,6,7,8,10,11,12,13,15,16,19,20,22

%N 1/4 of the number of islands of ones fitting in an n X n array symmetric about both diagonal and antidiagonal with all ones connected only either three adjacent vertically or three adjacent horizontally.

%e 8 X 8 example with 4 islands

%e .0.0.0.0.1.0.0.0

%e .0.0.0.0.0.1.1.1

%e .1.1.1.0.0.0.0.0

%e .0.0.0.1.0.0.0.0

%K nonn

%O 1,9

%A _R. H. Hardin_, Oct 20 2008