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 A259087 #22 Mar 21 2024 21:01:00 %S A259087 0,1,1,4,6,28,83,289,1030,3860,14154,53222,202001,771255,2945803, %T A259087 11304541,43564276,168413249,652292925,2531493604,9845752518, %U A259087 38372748112 %N A259087 Number of n-celled polyominoes which are of rectangular but not square type. %H A259087 T. R. Parkin, L. J. Lander, and D. R. Parkin, <a href="/A000104/a000104.pdf">Polyomino Enumeration Results</a>, presented at SIAM Fall Meeting, 1967, and accompanying letter from T. J. Lander (annotated scanned copy). See page 21. The 15th entry is not included because their value for A000105(15) was incorrect. %F A259087 a(n)+A259088(n) = A000105(n). %Y A259087 Cf. A259088, A000105. %K A259087 nonn,more %O A259087 1,4 %A A259087 _N. J. A. Sloane_, Jun 18 2015 %E A259087 a(15)-a(17) computed from A000105-A259088 by _Jean-François Alcover_, Dec 30 2019 %E A259087 a(18)-a(22) from _John Mason_, Nov 19 2021