|
%I #11 Sep 16 2018 09:56:36
%S 1,3,5,16,36,124,287,1043,2573,9448,24161,89827,235902,886047,2372494,
%T 8968829,24410414,92783928,255723571,976331352
%N Number of ways to build a contiguous building with n LEGO blocks of size 1 X 4 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.
%C The base block is not counted among the n and must be the only block in the bottom layer of the building.
%Y Cf. A112389, A123762 - A123827, A123829 - A123849.
%K nonn
%O 1,2
%A _Søren Eilers_, Oct 29 2006
%E a(14)-a(20) from _Søren Eilers_, Sep 16 2018
|
