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 A215826 #48 Oct 27 2023 21:44:48 %S A215826 1,1,41,3127,41813,1269900,45832761,1064557805,30860212081, %T A215826 928789262080,25020222581494,714819627084057,20574308184277971, %U A215826 576115800837801057,16381774291037991059,466431115279461257920,13190758349044182698371,374524994697062170913555 %N A215826 Number of ways in which a 9 X n grid can be tiled with trominoes. %H A215826 Alois P. Heinz, <a href="/A215826/b215826.txt">Table of n, a(n) for n = 0..700</a> (terms n = 1..42 from V. Raman) %H A215826 Project Euler, <a href="http://projecteuler.net/problem=161">Problem 161: Triominoes</a>. %Y A215826 Cf. A215827 (number of memoizations needed to calculate a(n)), A134438, A233290, A269664. %Y A215826 Column k=9 of A233320. %K A215826 nonn %O A215826 0,3 %A A215826 _V. Raman_, Aug 23 2012