%I #9 Dec 14 2019 21:23:40
%S 1,3,11,44,186,814,3656,16731,77705,365095,1731797,8279363,39845689,
%T 192852359,937986507,4581678031,22464030959,110509938701,545269104263,
%U 2697646445713,13378627003520,66495716465315,331167284581601,1652340114446553,8258197397705302
%N 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.
%H Rasmus Mølck Nilsson: <a href="https://www.math.ku.dk/english/research/tfa/ncg/paststudents/ms-theses/RMS_msthesis.pdf">On the number of flat LEGO structures</a>, Master's thesis in Mathematics, University of Copenhagen, 2016.
%Y Cf. A123764, but here no identification up to rotation is performed.
%K nonn
%O 1,2
%A _Søren Eilers_, Sep 12 2018