A123804 Number of ways, counted up to symmetry, to build a contiguous building with n LEGO blocks of size 1 X 7 which is flat, i.e., with all blocks in parallel position.

1, 7, 109, 1877, 35243, 685817, 13719483, 279714347, 5788634457

Offset: 1

Author

Søren Eilers, Oct 29 2006

Keywords

• nonn
• hard

Crossrefs

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