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A273988
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The number of slim, rectangular lattices of length n>=2.
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2
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1, 2, 6, 19, 78, 387, 2327, 16384, 132336, 1203145, 12146959, 134749221, 1628840129, 21308361378, 299940041508, 4520381905248, 72625922986869, 1239160455312246, 22377511072312218, 426411855436193451, 8550614540544797370, 179989316790109543775, 3968315581691624472787, 91451247683519227059456
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OFFSET
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2,2
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COMMENTS
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The initial term is the four element diamond shape lattice.
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LINKS
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FORMULA
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a(n) = 1/2*( A273596(n) + Sum_{k=1..floor(n/2)} binomial(n-k-1,k-1)*A000085(n-2k) ).
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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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