A123766 Number of ways to build a contiguous building with n LEGO blocks of size 1 X 2 on top of a fixed block of the same size.

7, 58, 625, 7198, 90045, 1171813, 15798521, 218322975, 3078005599, 44090886228, 639937519413

Offset

1,1

Comments

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

Links

Table of n, a(n) for n=1..11.

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.

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

Index entry for sequences related to LEGO blocks

Crossrefs

Sequence in context: A192940 A126130 A323254 * A362772 A005332 A132546

Adjacent sequences: A123763 A123764 A123765 * A123767 A123768 A123769

Keyword

nonn,hard,more

Author

Søren Eilers, Oct 29 2006

Status

approved