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Number of ways to build a contiguous building with n LEGO blocks of size 2 X 3 on top of a fixed block of the same size so that the building is symmetric after a rotation by 180 degrees.
64

%I #11 Nov 29 2017 03:38:18

%S 1,13,25,352,1006,15510,46928,744211,2479362

%N Number of ways to build a contiguous building with n LEGO blocks of size 2 X 3 on top of a fixed block of the same size so that the building is 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.

%H <a href="/wiki/Index_to_OEIS:_Section_Lc#LEGO">Index entry for sequences related to LEGO blocks</a>

%Y Cf. A112389, A123762 - A123827, A123829 - A123849.

%K nonn,more

%O 1,2

%A _Søren Eilers_, Oct 29 2006