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 A247743 #6 Feb 06 2017 18:59:32
%S A247743 0,0,0,0,48,528,4752,44080,408192,3738692,32818416,282587664,
%T A247743 2417602560,20523442012,172798010156,1443679767220,11992713950224,
%U A247743 99165736820120,816514750434924,6697254233908596,54745726513283448,446174778295639204,3626566397497170096
%N A247743 Total number of W shapes in all tilings of a 5 X n rectangle with pentominoes of any shape.
%H A247743 Alois P. Heinz, <a href="/A247743/b247743.txt">Table of n, a(n) for n = 0..500</a>
%H A247743 Wikipedia, <a href="https://en.wikipedia.org/wiki/Pentomino">Pentomino</a>
%F A247743 a(n) = Sum_{k>0} k * A247710(n,k).
%Y A247743 Cf. A174249, A233427, A247710.
%K A247743 nonn
%O A247743 0,5
%A A247743 _Alois P. Heinz_, Sep 23 2014