Number of ways, counted up to symmetry, to build a contiguous building with n LEGO blocks of size 1 X 2 which is flat, i.e., with all blocks in parallel position.

A123764

Number of ways, counted up to symmetry, to build a contiguous building with n LEGO blocks of size 1 X 2 which is flat, i.e., with all blocks in parallel position.

Terms

    a(0) =1a(1) =2a(2) =7a(3) =24a(4) =99a(5) =416a(6) =1854a(7) =8407a(8) =38970a(9) =182742a(10) =866442a(11) =4140607a(12) =19925401a(13) =96430625a(14) =469005432a(15) =2290860538a(16) =11232074043a(17) =55255074216a(18) =272634835875

External references