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A145956
Number of n X n binary arrays symmetric about both diagonal and antidiagonal with all ones connected only in a zee 1,1 1,2 2,2 2,3 in any orientation.
0
1, 1, 1, 1, 1, 3, 7, 13, 37, 103, 343, 1549, 7241, 37919, 236383, 1636125, 13465687, 128312593, 1395150187, 17424865195, 251739719221, 4153202993611, 79756129711801, 1753738354816013, 44633769685103851, 1301658659951823679
OFFSET
1,6
EXAMPLE
Maximal 8 X 8 example
.0.0.0.0.0.0.0.0
.0.0.0.0.1.1.0.0
.0.0.0.1.1.0.1.0
.0.0.1.0.0.1.1.0
.0.1.1.0.0.1.0.0
.0.1.0.1.1.0.0.0
.0.0.1.1.0.0.0.0
.0.0.0.0.0.0.0.0
CROSSREFS
Sequence in context: A177945 A147448 A146449 * A155225 A051842 A147447
KEYWORD
nonn
AUTHOR
R. H. Hardin, Oct 25 2008
STATUS
approved