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 A123792 #8 Jul 21 2017 13:16:55 %S A123792 9,91,1089,13726,182736,2493062,34865595,495114895,7127585291 %N A123792 Number of ways to build a contiguous building with n LEGO blocks of size 1 X 5 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 A123792 The base block is not counted among the n and must be the only block in the bottom layer of the building. %Y A123792 Cf. A112389, A123762 - A123827, A123829 - A123849. %K A123792 nonn,hard %O A123792 1,1 %A A123792 _Søren Eilers_, Oct 29 2006