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Number of free n-polyominoids, allowing corner-connections only.
5

%I #12 Nov 04 2023 18:24:49

%S 1,2,19,293,6590,168753

%N Number of free n-polyominoids, allowing corner-connections only.

%C Two squares are allowed to meet in an edge, but the structure must be connected through pure corner-connections (where the two squares meet in a single point) only. There are 3 such cases of size 3; see the linked illustration.

%H Pontus von Brömssen, <a href="/A365652/a365652.svg">Illustration for sizes 1..3</a>.

%H <a href="/index/Pol#polyominoes">Index entries for sequences related to polyominoes</a>.

%Y Cf. A075679 (polyominoids, edge-connections only), A365650 (corner- and edge-connections), A365653 (fixed).

%Y 27th row of A366766.

%K nonn,hard,more

%O 1,2

%A _Pontus von Brömssen_, Sep 17 2023