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A194596 Number of free non-polyominoes. 0

%I

%S 0,1,3,17,82,489,2923,18401,116848,753726,4898579,32085696,211398614,

%T 1400292492,9318028028,62259251309,417496576187

%N Number of free non-polyominoes.

%C Non-polyominoes are figures (like polyominoes), but are orthogonally connected at least in one vertex. So this number is equal to number of (free) n-polyplets minus number of free polyominoes: a(n) = A030222(n) - A000105(n).

%H Eric W. Weisstein, <a href="http://mathworld.wolfram.com/Polyplet.html">MathWorld: Polyplet</a>

%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

%O 1,3

%A _Jani Melik_, Aug 30 2011

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Last modified February 26 03:09 EST 2020. Contains 332272 sequences. (Running on oeis4.)