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A141487
Number of n X n binary matrices, symmetric under 90-degree rotation, with no more than 1 one in any 2 X 2 subblock.
1
1, 2, 1, 3, 4, 13, 17, 82, 167, 1029, 2594, 22033, 77729, 874498, 4050975, 61638683, 387821570, 7893076251, 66271702355, 1814566347320, 20521356444643, 753627817663469, 11423997447177546, 563598221301212705
OFFSET
0,2
LINKS
R. H. Hardin, Aug 09 2008, Table of n, a(n) for n = 0..30
CROSSREFS
Sequence in context: A001054 A375364 A218209 * A217103 A099866 A365228
KEYWORD
nonn
AUTHOR
R. H. Hardin, Aug 09 2008
STATUS
approved