A366001 Number of free polyominoids with n cells, allowing right-angled corner-connections and flat edge-connections.

1, 2, 18, 243, 4881, 111697, 2709778

Offset

1,2

Links

Table of n, a(n) for n=1..7.

Pontus von Brömssen, Illustration for sizes 1..3.

Wikipedia, Polyominoid.

Index entries for sequences related to polyominoes.

Crossrefs

See A365995 for further details and a table of related sequences.

Cf. A366002 (fixed).

24th row of A366766.

Sequence in context: A357603 A024486 A052635 * A259270 A168562 A117514

Adjacent sequences: A365998 A365999 A366000 * A366002 A366003 A366004

Keyword

nonn,hard,more

Author

Pontus von Brömssen, Sep 26 2023

Extensions

a(7) from Pontus von Brömssen, Oct 20 2025

Status

approved