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 A123808 #8 Jul 21 2017 13:15:55 %S A123808 13,190,3289,59970,1154985,22797643,461266481,9477047041 %N A123808 Number of ways to build a contiguous building with n LEGO blocks of size 1 X 7 on top of a fixed block of the same size so that the building is flat, i.e., with all blocks in parallel position. %C A123808 The base block is not counted among the n and must be the only block in the bottom layer of the building. %Y A123808 Cf. A112389, A123762 - A123827, A123829 - A123849. %K A123808 nonn,hard %O A123808 1,1 %A A123808 _Søren Eilers_, Oct 29 2006