A123849 Number of ways to build a contiguous building with n LEGO blocks of size 5 X 5 on top of a fixed block of the same size so that the building is symmetric after a rotation by 90 degrees.

1, 1, 1, 11, 21, 31, 41

Offset: 1

Author

Søren Eilers, Oct 29 2006

Keywords

• nonn
• more

Comments

The base block is not counted among the n and must be the only block in the bottom layer of the building.

Links

• 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.