OFFSET
1,1
COMMENTS
If more than two lines intersect in the same point, only one intersection is counted.
REFERENCES
For references and links see A288177.
LINKS
Lars Blomberg, Table of n, a(n) for n = 1..325 (The first 25 rows)
Lars Blomberg, Scott R. Shannon, N. J. A. Sloane, Graphical Enumeration and Stained Glass Windows, 1: Rectangular Grids, (2021). Also arXiv:2009.07918.
Hugo Pfoertner, Illustrations of Chamber Complexes up to 5 X 5.
Hugo Pfoertner, Illustration of intersection points up to 6 X 6.
EXAMPLE
Triangle starts with:
n=1: 5,
n=2: 13, 37,
n=3: 35, 121, 353,
n=4: 75, 265, 771, 1761,
n=5: 159, 587, 1755, 4039, 8917,
n=6: 275, 1019, 3075, 7035, 15419, 26773,
n=7: 477, 1797, 5469, 12495, 27229, 47685, 84497,
n=8: 755, 2823, 8693, 19831, 43333, 76357, 135075, 215545,
n=9: 1163, 4369, 13301, 30333, 66699, 117719, 207643, 331233, 508613,
...
CROSSREFS
KEYWORD
nonn,tabl
AUTHOR
Hugo Pfoertner, Jun 06 2017
EXTENSIONS
Corrected and extended by Hugo Pfoertner, Jul 20 2017
STATUS
approved