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 A269959 #6 Feb 06 2017 12:30:15 %S A269959 1,8266,379419508,25020222581494,1830607857363940042, %T A269959 137787968143635937039786,10448677822353537147395706384, %U A269959 793868918375370204415242288244707,60346488218332294539638857492286577712,4587865445075128062280066720936757293474915 %N A269959 Number of tilings of a 10 X 3n rectangle using 10n trominoes of any shape. %H A269959 Alois P. Heinz, <a href="/A269959/b269959.txt">Table of n, a(n) for n = 0..200</a> %H A269959 Wikipedia, <a href="https://en.wikipedia.org/wiki/Tromino">Tromino</a> %Y A269959 Trisection of column k=10 of A233320. %K A269959 nonn %O A269959 0,2 %A A269959 _Alois P. Heinz_, Mar 08 2016