Number of ways 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.

A319156

Number of ways 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) =3a(2) =11a(3) =44a(4) =186a(5) =814a(6) =3656a(7) =16731a(8) =77705a(9) =365095a(10) =1731797a(11) =8279363a(12) =39845689a(13) =192852359a(14) =937986507a(15) =4581678031a(16) =22464030959a(17) =110509938701a(18) =545269104263

External references