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Number of fixed hexagonal polyominoes with n cells and tree-like structure.
1

%I #8 Oct 08 2023 21:17:22

%S 1,3,9,29,99,348,1260,4644,17382,65822,251655,969819,3762517,14680890,

%T 57567228,226712655,896252850,3555116583,14144563158

%N Number of fixed hexagonal polyominoes with n cells and tree-like structure.

%H Sean A. Irvine, <a href="https://github.com/archmageirvine/joeis/blob/master/src/irvine/oeis/a066/A066331.java">Java program</a> (github)

%Y Cf. A001207 (all polyhexes), A038142 (free tree-like).

%K nonn,more

%O 1,2

%A _Jan Kristian Haugland_, Jan 01 2002

%E a(16)-a(19) from _Sean A. Irvine_, Oct 08 2023