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 A247120 #9 Feb 07 2017 10:42:11 %S A247120 1,0,4,0,16,32,76,384,386,2976,3952,20520,41104,136160,393624,1027072, %T A247120 3412146,8470840,27988904,74155272,230939032,655493408,1942645984, %U A247120 5765577688,16807041186,50708538824,148118970352,446903215688,1320213337712,3968685090000 %N A247120 Number of tilings of a 10 X n rectangle using 2n pentominoes of shape L. %H A247120 Wikipedia, <a href="https://en.wikipedia.org/wiki/Pentomino">Pentomino</a> %Y A247120 Cf. A174249, A233427. %K A247120 nonn %O A247120 0,3 %A A247120 _Alois P. Heinz_, Nov 19 2014