A123839 Number of ways, counted up to symmetry, to build a contiguous building with n LEGO blocks of size 4 X 4 which is symmetric after a rotation by 180 degrees.

1, 1, 21, 67, 1565, 6241, 137613, 630193, 13136926

Offset

1,3

Links

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

Crossrefs

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

Sequence in context: A219379 A168240 A123779 * A180758 A197121 A175461

Adjacent sequences: A123836 A123837 A123838 * A123840 A123841 A123842

Keyword

nonn

Author

Søren Eilers, Oct 29 2006

Status

approved