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%I #11 Nov 04 2023 18:24:58
%S 1,2,18,243,4881,111697
%N Number of free polyominoids with n cells, allowing right-angled corner-connections and flat edge-connections.
%H Pontus von Brömssen, <a href="/A366001/a366001.svg">Illustration for sizes 1..3</a>.
%H Wikipedia, <a href="https://en.wikipedia.org/wiki/Polyominoid">Polyominoid</a>.
%H <a href="/index/Pol#polyominoes">Index entries for sequences related to polyominoes</a>.
%Y See A365995 for further details and a table of related sequences.
%Y Cf. A366002 (fixed).
%Y 24th row of A366766.
%K nonn,hard,more
%O 1,2
%A _Pontus von Brömssen_, Sep 26 2023