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 A162678 #4 Jul 22 2025 06:56:18 %S A162678 0,2,42,937,26427,937126,40290848,2036152559,118202398712, %T A162678 7747410863508,565695467280668,45525704815211707,4002930269942820774, %U A162678 381750656962679848234,39244733577786597223238 %N A162678 Number of fixed strictly disconnected n-ominoes bounded (not necessarily tightly) by an n*n square. %C A162678 a(n) = A162676(n) - A001168(n) %e A162678 a(2)=2: the two rotations of the disconnected domino consisting of two squares connected at a vertex %Y A162678 Cf. A162676, A001168, A006770, A030222 %K A162678 nonn %O A162678 1,2 %A A162678 _David Bevan_, Jul 28 2009