A197551 - OEIS

A197551

Number of free poly-IH18-tiles (holes allowed) with n cells.

1, 1, 4, 10, 37, 147, 637, 2823, 13020, 60649, 286549, 1364667, 6547108, 31586568

(list; graph; refs; listen; history; text; internal format)

OFFSET

1,3

COMMENTS

Equivalently, polyhexes where two polyhexes are considered equivalent if and only if they are related by a translation, a rotation of order 3 or a reflection or glide reflection in a line perpendicular to the sides of the hexagons.

REFERENCES

Branko Grünbaum and G. C. Shephard, Tilings and Patterns. W. H. Freeman, New York, 1987, Sections 6.2 and 9.4.

LINKS

Table of n, a(n) for n=1..14.

CROSSREFS

Cf. A000228, A001207, A006535, A057973, A197549, A197550, A197552, A197553, A197554.

Sequence in context: A149189 A149190 A102755 * A046562 A240382 A220198

Adjacent sequences: A197548 A197549 A197550 * A197552 A197553 A197554

KEYWORD

hard,nonn

AUTHOR

Joseph Myers, Oct 16 2011

STATUS

approved