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 A264812 #13 Feb 06 2017 14:28:50 %S A264812 1,1,3,5,13,52,123,366,909,2444,7108,19157,53957,146826,400704, %T A264812 1115852,3059907,8475420,23369304,64225984,177572352,488839323, %U A264812 1349102071,3722419367,10255126169,28303059509,78013005366,215160477217,593488173404,1636220978049 %N A264812 Number of tilings of a 5 X n rectangle using n pentominoes of shapes P, I, X. %H A264812 Alois P. Heinz, <a href="/A264812/b264812.txt">Table of n, a(n) for n = 0..1000</a> %H A264812 Wikipedia, <a href="https://en.wikipedia.org/wiki/Pentomino">Pentomino</a> %e A264812 a(4) = 13: %e A264812 ._______. ._______. ._______. ._______. %e A264812 | | | | | | | | | | | | | ._| | %e A264812 | | | | | | ._| ._| | ._| | | |___| | %e A264812 | | | | | |_| |_| | |_| | | | | |___| %e A264812 | | | | | (1) | | | (4) | | | | (6) | ._| | (2) %e A264812 |_|_|_|_| |___|___| |_ _|_|_| |_|_____| . %e A264812 a(5) = 52: %e A264812 ._________. %e A264812 | |_. | %e A264812 | ._| |___| %e A264812 |_|_ _| | %e A264812 | |_| | (2) ... %e A264812 |_____|___| . %Y A264812 Cf. A174249, A233427, A234312, A234931, A247124, A247268, A247443, A249762, A264765, A278330. %K A264812 nonn %O A264812 0,3 %A A264812 _Alois P. Heinz_, Nov 25 2015