Number of ways to build a contiguous building with n LEGO blocks of size 2 X 2 on top of a fixed block of the same size so that the building is symmetric after a rotation by 180 degrees.
A123822
Number of ways to build a contiguous building with n LEGO blocks of size 2 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) =5a(2) =9a(3) =44a(4) =111a(5) =576a(6) =1541a(7) =8199a(8) =23750a(9) =127654a(10) =384817a(11) =2083235
External references
- oeis: A123822