A391551 Number of fixed polylozenges with n cells.

3, 12, 68, 423, 2772, 18841, 131490, 935568, 6755239, 49346427, 363894768, 2704572950

Offset

1,1

Comments

A cell of a polylozenge is a lozenge consisting of two adjacent equilateral triangles in the triangular grid.

There are three distinct orientations of a cell relative to a fixed triangular grid, so a(1) = 3.

Links

Table of n, a(n) for n=1..12.

Crossrefs

Cf. A056845 (free), A393906 (one-sided).

Sequence in context: A187118 A121812 A039750 * A365655 A366228 A393730

Adjacent sequences: A391548 A391549 A391550 * A391552 A391553 A391554

Keyword

nonn,more

Author

Pontus von Brömssen, Mar 10 2026

Status

approved