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 A123826 #7 Feb 15 2025 15:35:15 %S A123826 31,1165,57415,3060464,176633912,10625603236,661642082820 %N A123826 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. %C A123826 The base block is not counted among the n and must be the only block in the bottom layer of the building. %Y A123826 Cf. A112389, A123762 - A123827, A123829 - A123849. %K A123826 nonn,hard %O A123826 1,1 %A A123826 _Søren Eilers_, Oct 29 2006