Number of ways to build a contiguous building with n LEGO blocks of size 1 X 2 on top of a fixed block of the same size so that the building is flat, i.e., with all blocks in parallel position.

A123768

Number of ways to build a contiguous building with n LEGO blocks of size 1 X 2 on top of a fixed block of the same size so that the building is flat, i.e., with all blocks in parallel position.

Terms

    a(0) =3a(1) =10a(2) =39a(3) =160a(4) =693a(5) =3071a(6) =13953a(7) =64335a(8) =300749a(9) =1420116a(10) =6764691a(11) =32453268a(12) =156653477a(13) =760139341a(14) =3705381789a(15) =18134664515a(16) =89068494994a(17) =438841011495

External references