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A140422
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Half the number of n X n symmetric binary matrices with every 1 adjacent to some 0 horizontally or vertically and every 0 adjacent to some 1 horizontally or vertically.
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1
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1, 5, 47, 849, 29241, 1901849, 234932757, 55047807551, 24470603864937, 20637055514911557, 33018065501295740951, 100220335496292824426843, 577112450349963078523926227
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OFFSET
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2,2
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LINKS
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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STATUS
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approved
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