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 A219991 #6 Nov 28 2016 00:37:22 %S A219991 1,1,258,7827,619773,31411948,1973546988,111496884663,6652506271144, %T A219991 385840008972355,22714686725936048,1326699809920740144, %U A219991 77815956863006419783,4553929883329302973354,266826017253691963185320,15623876956054896455317089,915167189151722925761420274 %N A219991 Number of tilings of an 8 X n rectangle using dominoes and right trominoes. %H A219991 Alois P. Heinz, <a href="/A219991/b219991.txt">Table of n, a(n) for n = 0..200</a> %Y A219991 Column k=8 of A219987. %K A219991 nonn %O A219991 0,3 %A A219991 _Alois P. Heinz_, Dec 02 2012