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A145957
Number of n X n binary arrays symmetric about the diagonal and under 90-degree rotation 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, 1, 1, 1, 3, 3, 9, 9, 23, 23, 125, 125, 821, 821, 6239, 6239, 71403, 71403, 1048093, 1048093, 19913069, 19913069, 517074745, 517074745, 17642361171, 17642361171
OFFSET
1,9
EXAMPLE
Maximal 9 X 9 example:
0 0 1 0 0 0 1 0 0
0 0 1 1 0 1 1 0 0
1 1 0 1 0 1 0 1 1
0 1 1 0 0 0 1 1 0
0 0 0 0 0 0 0 0 0
0 1 1 0 0 0 1 1 0
1 1 0 1 0 1 0 1 1
0 0 1 1 0 1 1 0 0
0 0 1 0 0 0 1 0 0
CROSSREFS
Sequence in context: A146394 A147510 A146474 * A214439 A287479 A128019
KEYWORD
nonn
AUTHOR
R. H. Hardin, Oct 25 2008
STATUS
approved