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 A247736 #6 Feb 06 2017 18:42:26
%S A247736 0,1,2,11,122,2278,17502,140037,1250890,11184764,96901618,810143038,
%T A247736 6787465080,56871594099,473417649550,3913478050583,32192184170708,
%U A247736 264014564271675,2158561440821352,17592866753339355,142983916007396542,1159269824603687631,9378694043134778568
%N A247736 Total number of I shapes in all tilings of a 5 X n rectangle with pentominoes of any shape.
%H A247736 Alois P. Heinz, <a href="/A247736/b247736.txt">Table of n, a(n) for n = 0..500</a>
%H A247736 Wikipedia, <a href="https://en.wikipedia.org/wiki/Pentomino">Pentomino</a>
%F A247736 a(n) = Sum_{k>0} k * A247703(n,k).
%Y A247736 Cf. A174249, A233427, A247703.
%K A247736 nonn
%O A247736 0,3
%A A247736 _Alois P. Heinz_, Sep 23 2014