This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A123803 #10 Feb 15 2025 15:31:22 %S A123803 1,2,52,617,6052,86534,814679,12560687 %N A123803 Number of ways, counted up to symmetry, to build a contiguous building with n LEGO blocks of size 1 X 7 which is symmetric after a rotation by 180 degrees. %Y A123803 Cf. A112389, A123762 - A123827, A123829 - A123849. %K A123803 nonn,more %O A123803 1,2 %A A123803 _Søren Eilers_, Oct 29 2006