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A274208
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Sum of the areas of all bargraphs of site-perimeter n.
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2
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0, 0, 0, 0, 1, 0, 4, 6, 14, 36, 77, 168, 395, 851, 1921, 4254, 9461, 20991, 46619, 103360, 229461, 508731, 1128706, 2503028, 5552197, 12313707, 27313442, 60581866, 134384684, 298097515, 661300177, 1467072716, 3254847737, 7221496901, 16023112774, 35553756328
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OFFSET
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0,7
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COMMENTS
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A bargraph is a polyomino whose bottom is a segment of the nonnegative x-axis and whose upper part is a lattice path starting at (0,0) and ending with its first return to the x-axis using steps U=(0,1), D=(0,-1) and H=(1,0), where UD and DU are not allowed.
The site-perimeter of a polyomino is the number of exterior cells having a common edge with at least one polyomino cell.
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LINKS
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FORMULA
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a(n) = Sum_{k=floor((n-1)/2)..floor(((n-1)^2+3)/12)} k * A274207(n,k).
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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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