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 A247443 #28 Feb 06 2017 18:12:34 %S A247443 1,0,2,0,6,16,32,104,186,800,1700,4836,11186,29940,84388,208808, %T A247443 563364,1391664,3787510,9824684,25712276,66815444,173151378,457266220, %U A247443 1188536784,3113743272,8087358736,21152284376,55283003950,144314582896,376852311434,982507243820 %N A247443 Number of tilings of a 5 X n rectangle using n pentominoes of shapes F, L, Y. %H A247443 Alois P. Heinz, <a href="/A247443/b247443.txt">Table of n, a(n) for n = 0..1000</a> %H A247443 Alois P. Heinz, <a href="/A247443/a247443.txt">G.f. and Maple program for A247443</a> %H A247443 Wikipedia, <a href="https://en.wikipedia.org/wiki/Pentomino">Pentomino</a> %F A247443 G.f.: see link. %e A247443 a(5) = 16: %e A247443 ._._______. ._______._. %e A247443 | | ._____| |_. .___| | %e A247443 | |_| ._| | | |_| ._| | %e A247443 | |_. |_. | | |_. |_. | %e A247443 |___|_| | | | ._|_| |_| %e A247443 |_______|_| (*8) |_|_______| (*8) . %p A247443 # Maple program: see link. %Y A247443 Cf. A174249, A233427, A234312, A234931, A247680, A248102, A249762. %K A247443 nonn %O A247443 0,3 %A A247443 _Alois P. Heinz_, Sep 23 2014