A123795 Number of ways, counted up to symmetry, to build a contiguous building with n LEGO blocks of size 1x6 which is symmetric after a rotation by 180 degrees.

1, 1, 43, 289, 3796, 30757, 384465, 3363194

Offset

1,3

Links

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

Crossrefs

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

Sequence in context: A231226 A268259 A140012 * A364320 A346575 A217621

Adjacent sequences: A123792 A123793 A123794 * A123796 A123797 A123798

Keyword

nonn

Author

Søren Eilers, Oct 29 2006

Status

approved