Number of ways to build a contiguous building with n LEGO blocks of size 1 X 7 on top of a fixed block of the same size so that the building is symmetric after a rotation by 180 degrees.

A123807

Number of ways to build a contiguous building with n LEGO blocks of size 1 X 7 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) =2a(1) =28a(2) =104a(3) =1783a(4) =9593a(5) =187265a(6) =1093734

External references