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 flat, i.e., with all blocks in parallel position and symmetric after a rotation by 180 degrees.
A123809
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 flat, i.e., with all blocks in parallel position and symmetric after a rotation by 180 degrees.
Terms
- a(0) =1a(1) =4a(2) =7a(3) =34a(4) =85a(5) =461a(6) =1175a(7) =6871a(8) =18807a(9) =112406a(10) =318571a(11) =1936113a(12) =5653062a(13) =34848639a(14) =103771770a(15) =645701202a(16) =1955873614
External references
- oeis: A123809