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 A245660 #34 May 10 2023 10:55:22 %S A245660 1,0,0,0,1,0,0,1,1,0,2,1,2,4,5,4,12,13,20,29,52,67,106,173,269,375, %T A245660 658,991,1512,2425,3896,5902,9454,15146,23601,37050,59908,93777, %U A245660 148151,237228,375893,593773,948623,1508823,2393035,3812023,6083290,9666024,15404085,24592209 %N A245660 Number of unitary polyominoes without holes with n cells. A unitary polyomino is a polyomino whose edges all have length 1. %H A245660 John Mason, <a href="/A245660/a245660_3.pdf">Counting unitary polyominoes without holes</a> %H A245660 George Sicherman, <a href="https://sicherman.net/nunitary/nunitary.html">Catalogue of Unitary Polyominoes</a> %Y A245660 Cf. A245620, number of unitary polyominoes with n cells. %K A245660 nonn,hard,more %O A245660 1,11 %A A245660 _Joerg Arndt_, Jul 28 2014 %E A245660 Added a(16)-a(20), _George Sicherman_, Jul 29 2014 %E A245660 a(21)-a(43) from _John Mason_, Apr 21 2023 %E A245660 a(44)-a(50) from _John Mason_, Apr 26 2023