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A295771
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a(n) is the minimum size of a planar additive basis for the square [0,n]^2.
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2
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1, 3, 4, 7, 8, 11, 12, 14, 16, 19, 20, 23, 24, 26
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OFFSET
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0,2
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COMMENTS
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A planar additive basis is a set of points with nonnegative integer coordinates such that their pairwise sums cover a given rectangle of points with integer coordinates. Pairwise sums of a point with itself are included.
a(n) <= 2n+1, because there is an L-shaped basis of that size.
a(n) <= 2n if n is even and nonzero, because of a square-shaped "boundary basis" with sides at coordinates 0 and n/2.
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LINKS
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EXAMPLE
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a(3)=7: The square [0,3]^2 is covered by the pairwise sums of the L-shaped basis {(0,0),(1,0),(2,0),(3,0),(0,1),(0,2),(0,3)}, which has 7 elements.
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CROSSREFS
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A001212 concerns the one-dimensional problem.
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KEYWORD
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nonn,more
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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