A123772 - cp's OEIS frontend

A123772 Number of ways, counted up to symmetry, to build a contiguous building with n LEGO blocks of size 1 X 3 which is flat, i.e., with all blocks in parallel position.

%I A123772 #7 Jul 21 2017 15:35:51
%S A123772 1,3,17,107,761,5607,42730,331851,2618024,20895964,168398683,
%T A123772 1367838390,11184711448,91976811135
%N A123772 Number of ways, counted up to symmetry, to build a contiguous building with n LEGO blocks of size 1 X 3 which is flat, i.e., with all blocks in parallel position.
%Y A123772 Cf. A112389, A123762 - A123827, A123829 - A123849.
%K A123772 nonn,hard
%O A123772 1,2
%A A123772 _Søren Eilers_, Oct 29 2006

cp's OEIS Frontend

A123772 Number of ways, counted up to symmetry, to build a contiguous building with n LEGO blocks of size 1 X 3 which is flat, i.e., with all blocks in parallel position.