A112389 Number of ways, counted up to symmetry, to build a contiguous building with n LEGO blocks of size 2 X 4.

1, 24, 1560, 119580, 10166403, 915103765, 85747377755, 8274075616387, 816630819554486, 82052796578652749

Offset

1,2

Comments

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

References

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

Links

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.

Crossrefs

Cf. A112390, A272690.

Sequence in context: A063885 A019284 A333042 * A187634 A229430 A054777

Adjacent sequences: A112386 A112387 A112388 * A112390 A112391 A112392

Keyword

nonn,hard,more

Author

N. J. A. Sloane, Dec 06 2005

Extensions

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

Status

approved