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 A123840 #10 Dec 01 2021 01:10:55 %S A123840 1,1,1,1,13,19,25,165,713 %N A123840 Number of ways, counted up to symmetry, to build a contiguous building with n LEGO blocks of size 4 X 4 which is symmetric after a rotation by 90 degrees. %Y A123840 Cf. A112389, A123762 - A123827, A123829 - A123849. %K A123840 nonn,more %O A123840 1,5 %A A123840 _Søren Eilers_, Oct 29 2006