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 A194596 #26 Feb 16 2025 08:33:15 %S A194596 0,1,3,17,82,489,2923,18401,116848,753726,4898579,32085696,211398614, %T A194596 1400292492,9318028028,62259251309,417496576187 %N A194596 Number of free polyplets with n cells that are not polyominoes. %H A194596 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/Polyplet.html">Polyplet</a>. %F A194596 a(n) = A030222(n) - A000105(n). %e A194596 XX...X.X..X.. (the 3 for n=3) %e A194596 ..X...X....X. %e A194596 ............X %e A194596 a(3) = 5 - 2 = 3 %e A194596 a(4) = 22 - 5 = 17 %e A194596 a(5) = 94 - 12 = 82 %Y A194596 Cf. A030222, A000105, A006770 (fixed polyplets), A001168 (fixed polyominoes). %K A194596 nonn,more %O A194596 1,3 %A A194596 _Jani Melik_, Aug 30 2011