Number of ways to build a contiguous building with n LEGO blocks of size 1 X 6 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.
A123801
Number of ways to build a contiguous building with n LEGO blocks of size 1 X 6 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) =31a(4) =76a(5) =365a(6) =920a(7) =4691a(8) =12695a(9) =65708a(10) =184458a(11) =967195a(12) =2798734a(13) =14837523a(14) =43829052a(15) =234029147a(16) =703643181
External references
- oeis: A123801