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A048873
Number of non-isomorphic arrangements of n lines in the real projective plane such that the lines do not pass through a common point and no point belongs to more than 2 lines.
5
1, 1, 1, 4, 11
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OFFSET
3,4
COMMENTS
These are called simple arrangements.
REFERENCES
J. E. Goodman and J. O'Rourke, editors, Handbook of Discrete and Computational Geometry, CRC Press, 1997, p. 102.
B. Grünbaum, Arrangements and Spreads. American Mathematical Society, Providence, RI, 1972, p. 6.
LINKS
Table of n, a(n) for n=3..7.
CROSSREFS
Cf.
A003036
,
A048872
.
Sequence in context:
A326720
A307491
A356110
*
A091390
A321967
A230024
Adjacent sequences:
A048870
A048871
A048872
*
A048874
A048875
A048876
KEYWORD
nonn
,
nice
,
more
AUTHOR
N. J. A. Sloane
EXTENSIONS
The next term is conjectured to be 135.
STATUS
approved
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Last modified April 29 07:13 EDT 2024. Contains 372098 sequences. (Running on oeis4.)