A123846 Number of ways, counted up to symmetry, to build a contiguous building with n LEGO blocks of size 5x5 which is symmetric after a rotation by 90 degrees.

1, 1, 1, 1, 21, 31, 41, 421, 1937

Offset

1,5

Links

Table of n, a(n) for n=1..9.

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.CO/0504039

Crossrefs

Sequence in context: A067599 A342838 A261322 * A336383 A168000 A031889

Adjacent sequences: A123843 A123844 A123845 * A123847 A123848 A123849

Keyword

nonn

Author

Søren Eilers, Oct 29 2006

Status

approved