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 A364457 #65 Apr 05 2025 15:43:55 %S A364457 1,1,1,1,0,1,1,1,1,1,1,1,2,1,1,1,1,6,6,1,1,1,2,17,30,17,2,1,1,2,43, %T A364457 145,145,43,2,1,1,3,108,733,1352,733,108,3,1,1,4,280,3540,12688,12688, %U A364457 3540,280,4,1,1,5,727,17300,115958,226922,115958,17300,727,5,1 %N A364457 Number A(n,k) of tilings of a k X n rectangle using dominoes and trominoes (of any shape); square array A(n,k), n>=0, k>=0, read by antidiagonals. %H A364457 Alois P. Heinz, <a href="/A364457/b364457.txt">Table of n, a(n) for n = 0..350</a> %H A364457 Liang Kai, <a href="https://arxiv.org/abs/2503.17698">Solving tiling enumeration problems by tensor network contractions</a>, arXiv:2503.17698 [math.CO], 2025. %H A364457 Wikipedia, <a href="https://en.wikipedia.org/wiki/Domino_(mathematics)">Domino (mathematics)</a> %H A364457 Wikipedia, <a href="https://en.wikipedia.org/wiki/Tromino">Tromino</a> %F A364457 A(n,k) = A(k,n). %e A364457 A(3,2) = A(2,3) = 6: %e A364457 .___. .___. .___. .___. .___. .___. %e A364457 | | | |___| | | | |___| | ._| |_. | %e A364457 | | | |___| |_|_| | | | |_| | | |_| %e A364457 |_|_| |___| |___| |_|_| |___| |___| . %e A364457 . %e A364457 Square array A(n,k) begins: %e A364457 1, 1, 1, 1, 1, 1, 1, 1, ... %e A364457 1, 0, 1, 1, 1, 2, 2, 3, ... %e A364457 1, 1, 2, 6, 17, 43, 108, 280, ... %e A364457 1, 1, 6, 30, 145, 733, 3540, 17300, ... %e A364457 1, 1, 17, 145, 1352, 12688, 115958, 1075397, ... %e A364457 1, 2, 43, 733, 12688, 226922, 3927233, 68846551, ... %e A364457 1, 2, 108, 3540, 115958, 3927233, 128441094, 4263997124, ... %e A364457 1, 3, 280, 17300, 1075397, 68846551, 4263997124, 267855152858, ... %Y A364457 Columns (or rows) k=0-10 give: A000012, A182097(n) = A000931(n+3), A019439, A364460, A364155, A364556, A364616, A364617, A364632, A364638, A364640. %Y A364457 Main diagonal gives A364504. %Y A364457 Cf. A219866, A219987, A233320. %K A364457 nonn,tabl %O A364457 0,13 %A A364457 _Alois P. Heinz_, Jul 25 2023 %E A364457 Terms n,k>=4 had to be corrected as was pointed out by _Martin Fuller_ and _David Radcliffe_ - _Alois P. Heinz_, Apr 05 2025