A123781 - cp's OEIS frontend

A123781 Number of ways, counted up to symmetry, to build a contiguous building with n LEGO blocks of size 1 X 4 which is flat, i.e., with all blocks in parallel position and symmetric after a rotation by 180 degrees.

%I A123781 #12 Sep 12 2018 05:30:04
%S A123781 1,1,5,7,41,65,384,649,3853,6745,40209,72334,431188,791144,4717533,
%T A123781 8787824,52396271,98784645
%N A123781 Number of ways, counted up to symmetry, to build a contiguous building with n LEGO blocks of size 1 X 4 which is flat, i.e., with all blocks in parallel position and symmetric after a rotation by 180 degrees.
%Y A123781 Cf. A112389, A123762 - A123827, A123829 - A123849.
%K A123781 nonn,more
%O A123781 1,3
%A A123781 _Søren Eilers_, Oct 29 2006
%E A123781 More terms by _Søren Eilers_, Sep 12 2018

cp's OEIS Frontend

A123781 Number of ways, counted up to symmetry, to build a contiguous building with n LEGO blocks of size 1 X 4 which is flat, i.e., with all blocks in parallel position and symmetric after a rotation by 180 degrees.