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 symmetric after a rotation by 180 degrees.
A123767
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 symmetric after a rotation by 180 degrees.
Terms
- a(0) =1a(1) =4a(2) =7a(3) =28a(4) =67a(5) =289a(6) =723a(7) =3185a(8) =8677a(9) =38580a(10) =109143a(11) =489496a(12) =1430283
External references
- oeis: A123767