A123789 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 and symmetric after a rotation by 180 degrees.

1, 1, 5, 7, 49, 77, 572, 949, 7245, 12361, 96063, 167564, 1313467, 2327488, 18365795, 32936281, 261111133, 472694546

Offset: 1

Author

Søren Eilers, Oct 29 2006

Keywords

• nonn
• more

Crossrefs

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

Extensions

More terms by Søren Eilers, Sep 12 2018