A123845 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 180 degrees.

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

Offset

1,3

Links

Table of n, a(n) for n=1..8.

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: A023277 A299109 A302542 * A297722 A042642 A172075

Adjacent sequences: A123842 A123843 A123844 * A123846 A123847 A123848

Keyword

nonn

Author

Søren Eilers, Oct 29 2006

Status

approved