A123840 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 90 degrees.

1, 1, 1, 1, 13, 19, 25, 165, 713

Offset

1,5

Links

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

Crossrefs

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

Sequence in context: A250293 A058898 A227092 * A258589 A103804 A063640

Adjacent sequences: A123837 A123838 A123839 * A123841 A123842 A123843

Keyword

nonn,more

Author

Søren Eilers, Oct 29 2006

Status

approved