A123847 Number of ways to build a contiguous building with n LEGO blocks of size 5x5 on top of a fixed block of the same size.

81, 7981, 1031121, 144390851, 21872530449, 3453512003039

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..6.

M. Abrahamsen and S. Eilers, On the asymptotic enumeration of LEGO Structures, Exper. Math. 20 (2) (2011) 145-152

Durhuus and S. Eilers, On the entropy of LEGO, arXiv:math.CO/0504039

Crossrefs

Sequence in context: A186132 A206504 A046172 * A115443 A328089 A186527

Adjacent sequences: A123844 A123845 A123846 * A123848 A123849 A123850

Keyword

nonn,hard

Author

Søren Eilers, Oct 29 2006

Status

approved