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 A343595 #19 May 24 2021 16:33:28 %S A343595 1,1,2,7,26,162,1096,12210,149384,2979716,65702176,2347717180, %T A343595 93123644320,5962338902536,424966024145024,48757525297347464, %U A343595 6240064849995542656,1282987881672304949776,294690971817685508825600,108580010933558879525595504 %N A343595 a(n) is the number of axially symmetric tilings of the order-n Aztec Diamond by square tetrominoes and Z-shaped tetrominoes, not counting rotations and reflections as distinct. %C A343595 No tiling is symmetric to both the x- and the y-axis. %C A343595 No tiling is symmetric to an oblique symmetry axis of the diamond. %C A343595 If a tiling is symmetric to the x-axis then a reflection over the y-axis is equal to a rotation by 180 degrees. %C A343595 The number of tilings is 4 * a(n) if rotations are counted as distinct. %C A343595 All tilings have exactly the minimum number of square tetrominoes given by ceiling(n/2). %H A343595 James Propp, <a href="https://www.jstor.org/stable/2691169">A Pedestrian Approach to a Method of Conway, or, A Tale of Two Cities</a>, Mathematics Magazine, Vol. 70, No. 5 (Dec., 1997), 327-340. %H A343595 Walter Trump, <a href="/A343595/a343595.pdf">Axially symmetric Aztec diamond tilings</a> %Y A343595 Cf. A342907. %K A343595 nonn %O A343595 1,3 %A A343595 _Walter Trump_, Apr 21 2021