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 A246902 #15 May 02 2022 09:55:04 %S A246902 1,1,0,28,200,856,2164,5584,13632,23608,27804,16412,4040 %N A246902 Number of tilings of a 5 X n rectangle using n pentominoes of distinct shapes. %H A246902 Wikipedia, <a href="https://en.wikipedia.org/wiki/Pentomino">Pentomino</a> %e A246902 a(3) = 28: 4 orientations of each of the following 7 patterns: %e A246902 ._____. ._____. ._____. ._____. ._____. ._____. ._____. %e A246902 |___. | | | | |_. ._| | .___| | | | |_. | | ._| | %e A246902 | | | | | | ._| | | | | | | | | ._| | | |___| | |_. | %e A246902 | | |_| | |_| | | |_| | |_| ._| |_| ._| |_. ._| |___| | %e A246902 | |_. | |___| | | |_. | | |_| | | |_| | | |_| | | |_| %e A246902 |___|_| |_____| |___|_| |_____| |_____| |_____| |_____| . %Y A246902 Cf. A174249, A233427. %K A246902 nonn,fini,full %O A246902 0,4 %A A246902 _Alois P. Heinz_, Nov 16 2014