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 A247103 #20 Feb 07 2017 10:22:25 %S A247103 1,1,3,11,33,166,589,2216,8935,33984,137056,539085,2100341,8324716, %T A247103 32607928,128652672,507032667,1992083368,7853132654,30894420646, %U A247103 121642017784,479048967517,1885229164497,7423732617043,29223734864421,115048209160729,452968829090506 %N A247103 Number of tilings of a 5 X n rectangle using n pentominoes of shapes I, N, P, U, T. %H A247103 Alois P. Heinz, <a href="/A247103/b247103.txt">Table of n, a(n) for n = 0..1000</a> %H A247103 Wikipedia, <a href="https://en.wikipedia.org/wiki/Pentomino">Pentomino</a> %e A247103 a(3) = 11: %e A247103 ._____. ._____. ._____. ._____. %e A247103 | | | | | | | | | | |_. | %e A247103 | | | | | ._| | | | ._| | |___| %e A247103 | | | | |_| ._| | |_| | | .___| %e A247103 | | | | | |_| | | | | |_| | %e A247103 |_|_|_| (1) |_____| (4) |_|___| (4) |_____| (2) . %Y A247103 Cf. A174249, A233427, A247196. %K A247103 nonn %O A247103 0,3 %A A247103 _Alois P. Heinz_, Nov 20 2014