Number of ways to build a contiguous building with n LEGO blocks of size 5 X 5 on top of a fixed block of the same size so that the building is symmetric after a rotation by 180 degrees.

A123848

Number of ways to build a contiguous building with n LEGO blocks of size 5 X 5 on top of a fixed block of the same size so that the building is symmetric after a rotation by 180 degrees.

Terms

    a(0) =1a(1) =29a(2) =57a(3) =1955a(4) =5805a(5) =222291a(6) =694961

External references