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A141445
Number of n X n integer matrices, symmetric under 180 degree rotation, with adjacent elements differing by no more than 1, counting matrices differing by a constant only once.
0
1, 3, 45, 597, 42787, 2695803, 923529659, 278451121903, 457744547778601, 663065487350675885
OFFSET
1,2
CROSSREFS
Sequence in context: A060242 A271236 A270064 * A076140 A131568 A287031
KEYWORD
nonn
AUTHOR
R. H. Hardin, Aug 06 2008
STATUS
approved