A123811 Number of ways, counted up to symmetry, to build a contiguous building with n LEGO blocks of size 1x8 which is symmetric after a rotation by 180 degrees.

1, 1, 73, 893, 11257, 167129, 1969619

Offset

1,3

Links

Table of n, a(n) for n=1..7.

Crossrefs

Cf. A112389, A123762 - A123827, A123829 - A123849.

Sequence in context: A104907 A296024 A254136 * A057522 A320205 A305549

Adjacent sequences: A123808 A123809 A123810 * A123812 A123813 A123814

Keyword

nonn

Author

Søren Eilers, Oct 29 2006

Status

approved