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A341630 Number of fixed polyiamonds of area n without holes. 1
2, 3, 6, 14, 36, 94, 250, 675, 1832, 5005, 13746, 37901, 104902, 291312, 811346, 2265905, 6343854, 17801383, 50057400, 141034248, 398070362, 1125426581, 3186725646, 9036406687, 25658313188, 72946289247, 207628101578, 591622990214, 1687527542874, 4818113792640 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Equivalently, closed self-avoiding paths on the hexagonal net, where rotations and reflections of the whole path are not allowed and there is no selected starting point, with enclosed area n.

LINKS

Andrey Zabolotskiy, Table of n, a(n) for n = 1..60 (from Iwan Jensen's table)

Anthony J. Guttman, editor, Polygons, Polyominoes and Polycubes, LNP 775, Springer, 2009. See Table 16.8 "Triangular lattice SAP by area" on p. 476 with reference "Iwan Jensen, Unpublished".

Index entries for sequences related to A2 = hexagonal = triangular lattice

CROSSREFS

Cf. A001420 (polyiamonds with holes allowed; first deviates at n=9), A036418 (polyiamonds with given perimeter, i.e. paths with given length), A070765 (free polyiamonds, i.e. reduced for symmetry: rotations and reflections are allowed), A006724 (analog for square lattice).

Sequence in context: A080408 A275774 A319323 * A001420 A337186 A049339

Adjacent sequences:  A341627 A341628 A341629 * A341631 A341632 A341633

KEYWORD

nonn

AUTHOR

Andrey Zabolotskiy, Feb 16 2021

STATUS

approved

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Last modified April 21 14:32 EDT 2021. Contains 343154 sequences. (Running on oeis4.)