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A006065 Maximal number of 4-tree rows in n-tree orchard problem.
(Formerly M0290)
0, 0, 0, 1, 1, 1, 2, 2, 3, 5, 6, 7, 9, 10, 12, 15, 16, 18, 20, 23 (list; graph; refs; listen; history; text; internal format)



Maximum number of rows with exactly 4 trees in each row if there are n trees in the orchard.

For further references and links see A003035.


S. A. Burr, B. Grünbaum and N. J. A. Sloane, The Orchard Problem, Geometriae Dedicata, 2 (1974), 397-424.

M. Gardner, Time Travel and Other Mathematical Bewilderments. Freeman, NY, 1988, Chap. 22.

Grünbaum, Branko, and J. F. Rigby. "The real configuration (214)." Journal of the London Mathematical Society 2.2 (1990): 336-346. [Shows a(21) >= 21.]

F. Levi, Geometrische Konfigurationen, Hirzel, Leipzig, 1929.

Xianzu Lin, A new result about orchard-planting problem, Preprint, 2005. [Shows a(20) >= 23.]

N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).

For further references and links see A003035.


Table of n, a(n) for n=1..20.

P. Berloquin, a(12) >= 7 (from an article in Jeux & Strategies from 1983 - see Fig. 10)

S. A. Burr, B. Grünbaum and N. J. A. Sloane, The Orchard Problem, Geometriae Dedicata, 2 (1974), 397-424.

Du, Zhao Hui, Code to verify a(13) to a(16) for orchard planting problem

Du, Zhao Hui, Link to one of the optimal results from 13~17 trees

Du, Zhao Hui, A chinese webpage for the problem

Noam D. Elkies, On some points-and-lines problems and configurations, arXiv:math/0612749 [math.MG], 2006

Erich Friedman, Table of values and bounds for up to 25 trees

Xianzu Lin, Illustration showing that a(20) >= 23 [The points S and T are at infinity]

Ed Pegg, Jr., Cultivating New Solutions for theOrchard-Planting Problem, 2018.

Eric Weisstein's World of Mathematics, Orchard-Planting Problem.


Cf. A003035, A008997.

Sequence in context: A227191 A214045 A172992 * A218933 A266746 A096981

Adjacent sequences:  A006062 A006063 A006064 * A006066 A006067 A006068




N. J. A. Sloane


a(13)-a(15) from Du, Zhao Hui, Aug 24 2008

a(17) from Du, Zhao Hui, Nov 11 2008

a(18) from Du, Zhao Hui, Nov 25 2008

a(19) from Du, Zhao Hui, Dec 17 2009

a(20) from Du, Zhao Hui, Feb 01 2010



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Last modified February 24 21:22 EST 2018. Contains 299628 sequences. (Running on oeis4.)