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 A339848 #29 Apr 26 2025 15:27:07 %S A339848 1,1,1,1,3,6,16,27,44,70 %N A339848 Number of distinct free polyominoes that fit in an n X n square but are not a proper sub-polyomino of any polyomino that fits in the square. %C A339848 A polyomino A is a proper sub-polyomino of B if one or more cells can be added to A to form B. %C A339848 Except for the n X n polyomino that fills the square all of the other polyominoes must have their edges aligned at an angle to the sides of the square. %C A339848 This counts the minimum subset of polyominoes needed to produce A268427 - that sequence counts the sub-polyominoes of this sequence. %H A339848 John Mason, <a href="/A268427/a268427_1.pdf">Explanation of a(5)</a> %H A339848 Talmon Silver, <a href="/A268427/a268427_2.pdf">Computing a(6)</a> %H A339848 Talmon Silver, <a href="https://drive.google.com/drive/folders/1AJJ8uhgdHhmpb-IKf_MLsIZgqXLD-Bth">Programs</a> %e A339848 For n=1, 2, 3, 4 the only polyominoes are the n X n polyominoes. Thus, a(1)=a(2)=a(3)=a(4)=1. %e A339848 For n=5 and n=6 all of the other polyominoes are shown in the links. %Y A339848 Cf. A268427. %K A339848 nonn,more %O A339848 1,5 %A A339848 _Talmon Silver_, Dec 19 2020