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A151522 Number of 1-sided polyrhombs with n cells. 3
1, 2, 4, 13, 35, 120, 392, 1405, 4998, 18378, 67792, 253509, 952534, 3604624, 13699554, 52304807, 200406370, 770442286 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

Also counts 1-sided polyrects.

LINKS

Table of n, a(n) for n=1..18.

Ed Pegg, Jr., Illustrations of polyforms

Eric Weisstein's World of Mathematics, Polyrhomb

Eric Weisstein's World of Mathematics, Polyrect

CROSSREFS

Polyominoes by group of symmetries relating shapes considered the same: A000105 (all symmetries), A001168 (translations only), A000988 (rotations and translations), A056780 (horizontal and vertical reflections, rotations of order 2 and translations), A056783 (reflections in either diagonal, rotations of order 2 and translations), A151522 (rotations of order 2 and translations), A151525 (reflections in a horizontal line and translations), A182645 (reflections in a NE-SW diagonal line and translations)

Sequence in context: A189590 A189597 A148235 * A148236 A148237 A148238

Adjacent sequences:  A151519 A151520 A151521 * A151523 A151524 A151525

KEYWORD

nonn,hard,more

AUTHOR

Ed Pegg Jr, May 13 2009

EXTENSIONS

Edited and a(13)-a(18) by Joseph Myers, Nov 24 2010

STATUS

approved

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Last modified April 25 10:11 EDT 2017. Contains 285379 sequences.