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Number of ways, counted up to symmetry, to build a contiguous building with n LEGO blocks of size 2 X 4.
67

%I #59 Jun 01 2024 11:14:02

%S 1,24,1560,119580,10166403,915103765,85747377755,8274075616387,

%T 816630819554486,82052796578652749

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

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

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

%H M. Abrahamsen and S. Eilers, <a href="http://dx.doi.org/10.1080/10586458.2011.564539">On the asymptotic enumeration of LEGO structures</a>, Exper. Math. 20 (2) (2011) 145-152.

%H B. Durhuus and S. Eilers, <a href="http://arxiv.org/abs/math/0504039">On the entropy of LEGO</a>, arXiv:math/0504039 [math.CO], 2005.

%H B. Durhuus and S. Eilers, <a href="http://dx.doi.org/10.1007/s12190-013-0730-9">On the entropy of LEGO</a>, J. Appl. Math. Comput. 45 (1-2) (2014), 433-448.

%H S. Eilers, <a href="http://www.jstor.org/stable/10.4169/amer.math.monthly.123.5.415">The LEGO counting problem</a>, Amer. Math. Monthly, 123 (May 2016), 415-426.

%H S. Eilers and M. Abrahamsen, <a href="http://www.math.ku.dk/~eilers/papers/eclbii.pdf">Efficient counting of LEGO structures</a>, March 30 2007.

%H <a href="/wiki/Index_to_OEIS:_Section_Lc#LEGO">Index entry for sequences related to LEGO blocks</a>.

%Y Cf. A112390, A272690.

%K nonn,hard,more

%O 1,2

%A _N. J. A. Sloane_, Dec 06 2005

%E Thanks to _Gerald McGarvey_, _Christian Schroeder_ and _Jud McCranie_, who contributed to this entry.

%E a(8) from _Søren Eilers_, Oct 29 2006

%E a(9) from _Johan Nilsson_, Jan 06 2014

%E a(10) from _Matthias Simon_, Apr 06 2018