A123788 Number of ways, counted up to symmetry, to build a contiguous building with n LEGO blocks of size 1 X 5 which is flat, i.e., with all blocks in parallel position.

1, 5, 53, 623, 8075, 108463, 1499542, 21128897, 302219695, 4373563505

Offset: 1

Author

Søren Eilers, Oct 29 2006

Keywords

• nonn
• hard

Crossrefs

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