A066331 Number of fixed hexagonal polyominoes with n cells and tree-like structure.

1, 3, 9, 29, 99, 348, 1260, 4644, 17382, 65822, 251655, 969819, 3762517, 14680890, 57567228, 226712655, 896252850, 3555116583, 14144563158

Offset

1,2

Links

Table of n, a(n) for n=1..19.

Sean A. Irvine, Java program (github)

Crossrefs

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

Sequence in context: A001893 A238979 A151030 * A099780 A006134 A074526

Adjacent sequences: A066328 A066329 A066330 * A066332 A066333 A066334

Keyword

nonn,more

Author

Jan Kristian Haugland, Jan 01 2002

Extensions

a(16)-a(19) from Sean A. Irvine, Oct 08 2023

Status

approved