
REFERENCES

P. Brass et al., Research Problems in Discrete Geometry, Springer, 2005.
S. A. Burr, in The Mathematical Gardner, Ed. D. A. Klarner, p. 94, Wadsworth, 1981.
S. A. Burr, B. Grünbaum and N. J. A. Sloane, The Orchard Problem, Geometriae Dedicata, 2 (1974), 397424.
H. E. Dudeney, Amusements in Mathematics, Nelson, London, 1917, page 56.
M. Gardner, Time Travel and Other Mathematical Bewilderments. Freeman, NY, 1988, Chap. 22.
B. Grünbaum, Arrangements and Spreads. American Mathematical Society, Providence, RI, 1972, p. 22.
John Jackson, Rational Amusements for Winter Evenings, London, 1821.
N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).


LINKS

Table of n, a(n) for n=1..14.
S. A. Burr, B. Grünbaum and N. J. A. Sloane, The Orchard Problem, Geometriae Dedicata, 2 (1974), 397424.
Z. H. Du, Orchard Planting Problem [From Du, Zhao Hui, Nov 20 2008] [Seems to concentrate on the 4 trees per line version.  N. J. A. Sloane, Oct 16 2010]
Noam D. Elkies, On some pointsandlines problems and configurations, arXiv:math/0612749 [math.MG], 2006; [Concerned with other versions of the problem].
B. Green, T. Tao, On sets defining few ordinary lines, arXiv:1208.4714. (Shows that a(n) = [n(n3)/6]+1 for all sufficiently large n.)
G. B. Purdy and J. W. Smith, Lines, circles, planes and spheres, Discrete Comput. Geom., 44 (2010), 860882.
N. J. A. Sloane, Illustration of initial terms (from GrünbaumBurrSloane paper)
Eric Weisstein's World of Mathematics, OrchardPlanting Problem.
