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A112389 Number of ways, counted up to symmetry, to build a contiguous building with n LEGO blocks of size 2 X 4. 67
1, 24, 1560, 119580, 10166403, 915103765, 85747377755, 8274075616387, 816630819554486, 82052796578652749 (list; graph; refs; listen; history; text; internal format)



a(6) is often quoted as 102981500, but this is incorrect.


Anthony Lane, The Joy of Bricks, The New Yorker, Apr 27-May 04, 1998, pp. 96-103.


Table of n, a(n) for n=1..10.

M. Abrahamsen and S. Eilers, On the asymptotic enumeration of LEGO structures, Exper. Math. 20 (2) (2011) 145-152.

B. Durhuus and S. Eilers, On the entropy of LEGO, arXiv:math/0504039 [math.CO], 2005.

B. Durhuus and S. Eilers, On the entropy of LEGO, J. Appl. Math. Comput. 45 (1-2) (2014), 433-448.

S. Eilers, The LEGO counting problem, Amer. Math. Monthly, 123 (May 2016), 415-426.

S. Eilers and M. Abrahamsen, Efficient counting of LEGO structures, March 30 2007.

Index entry for sequences related to LEGO blocks


Cf. A112390, A272690.

Sequence in context: A063885 A019284 A333042 * A187634 A229430 A054777

Adjacent sequences:  A112386 A112387 A112388 * A112390 A112391 A112392




N. J. A. Sloane, Dec 06 2005


Thanks to Gerald McGarvey, Christian Schroeder and Jud McCranie who contributed to this entry.

a(8) from Søren Eilers, Oct 29 2006

a(9) from Johan Nilsson, Jan 06 2014

a(10) from Matthias Simon, Apr 06 2018



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Last modified June 16 14:41 EDT 2021. Contains 345057 sequences. (Running on oeis4.)