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A141225 Number of points having maximal visibility in a square n x n lattice. +0
5
1, 4, 1, 4, 8, 16, 8, 12, 16, 36, 9, 60, 16, 16, 8, 12, 12, 12, 12, 36, 16, 16, 25, 4, 16, 8, 5, 12, 24, 64, 12, 8, 4, 4, 25, 16, 4, 8, 1, 20, 16, 4, 20, 12, 4, 4, 9, 8, 4, 4, 4, 4, 12, 4, 4, 4, 4, 12, 9, 4, 8, 4, 8, 12, 8, 4, 4, 8, 4, 16, 12, 20, 4, 8, 4, 4, 16, 4, 4, 4, 4, 4, 4, 4, 4, 4, 8, 4, 4 (list; graph; listen)
OFFSET

1,2

COMMENT

Sequence A141224 gives the maximum number of points visible from some point. By symmetry, when a(n) is odd, the central point in the lattice can see the maximal number of points. When a(n)=1, the central point is the only such point. See A141226 for the n x n lattices that have such a central point.

LINKS

T. D. Noe, Table of n, a(n) for n=1..1000

MATHEMATICA

Table[mx=0; pts=0; Do[cnt=0; Do[If[GCD[c-a, d-b]<2, cnt++ ], {a, n}, {b, n}]; If[cnt>mx, mx=cnt; pts=1, If[cnt==mx, pts++ ]], {c, n}, {d, n}]; pts, {n, 20}]

CROSSREFS

Sequence in context: A072812 A162956 A131112 this_sequence A079185 A133819 A021245

Adjacent sequences: A141222 A141223 A141224 this_sequence A141226 A141227 A141228

KEYWORD

nonn

AUTHOR

T. D. Noe (noe(AT)sspectra.com), Jun 15 2008

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Last modified November 23 17:09 EST 2009. Contains 167438 sequences.


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