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 A233340 #9 Feb 07 2017 17:26:05 %S A233340 1,62,8342,1269900,198253934,31111319376,4887323351972, %T A233340 767919868804309,120664440361104580,18960353496615710993, %U A233340 2979300461790704311162,468147088780110777732830,73561466714064126023807694,11558951424929920406557632356,1816295465197137076501207582877 %N A233340 Number of tilings of a 5 X 3n rectangle using 5n trominoes of any shape. %H A233340 Alois P. Heinz, <a href="/A233340/b233340.txt">Table of n, a(n) for n = 0..400</a> %H A233340 Alois P. Heinz, <a href="/A233340/a233340.txt">G.f. for A233340</a> %H A233340 Wikipedia, <a href="https://en.wikipedia.org/wiki/Tromino">Tromino</a> %F A233340 G.f.: see link above. %Y A233340 Trisection of column k=5 of A233320. %K A233340 nonn %O A233340 0,2 %A A233340 _Alois P. Heinz_, Dec 07 2013