A123845 - OEIS

A123845

Number of ways, counted up to symmetry, to build a contiguous building with n LEGO blocks of size 5 X 5 which is symmetric after a rotation by 180 degrees.

%I #9 Feb 15 2025 15:37:14

%S 1,1,29,143,3497,22303,503847,3778105

%N Number of ways, counted up to symmetry, to build a contiguous building with n LEGO blocks of size 5 X 5 which is symmetric after a rotation by 180 degrees.

%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.CO/0504039

%K nonn

%O 1,3

%A _Søren Eilers_, Oct 29 2006