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 A247735 #7 Feb 06 2017 18:41:02
%S A247735 0,0,0,4,68,744,7088,69176,658776,5995348,52831448,458439732,
%T A247735 3944077760,33606901296,283630894720,2375471834288,19779055344468,
%U A247735 163866917256420,1351464466008112,11100931884955344,90860898121739864,741378713523090200,6032337718479599100
%N A247735 Total number of F shapes in all tilings of a 5 X n rectangle with pentominoes of any shape.
%H A247735 Alois P. Heinz, <a href="/A247735/b247735.txt">Table of n, a(n) for n = 0..500</a>
%H A247735 Wikipedia, <a href="https://en.wikipedia.org/wiki/Pentomino">Pentomino</a>
%F A247735 a(n) = Sum_{k>0} k * A247702(n,k).
%Y A247735 Cf. A174249, A233427, A247702.
%K A247735 nonn
%O A247735 0,4
%A A247735 _Alois P. Heinz_, Sep 23 2014