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%I #25 Mar 29 2023 17:47:39
%S 0,1,3,17,82,489,2923,18401,116848,753726,4898579,32085696,211398614,
%T 1400292492,9318028028,62259251309,417496576187
%N Number of free polyplets with n cells that are not polyominoes.
%H Eric Weisstein's World of Mathematics, <a href="http://mathworld.wolfram.com/Polyplet.html">Polyplet</a>.
%F a(n) = A030222(n) - A000105(n).
%e XX...X.X..X.. (the 3 for n=3)
%e ..X...X....X.
%e ............X
%e a(3) = 5 - 2 = 3
%e a(4) = 22 - 5 = 17
%e a(5) = 94 - 12 = 82
%Y Cf. A030222, A000105, A006770 (fixed polyplets), A001168 (fixed polyominoes).
%K nonn,more
%O 1,3
%A _Jani Melik_, Aug 30 2011