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A151522 Number of 1-sided polyrhombs with n cells. 5
1, 2, 4, 13, 35, 120, 392, 1405, 4998, 18378, 67792, 253509, 952534, 3604624, 13699554, 52304807, 200406370, 770442286, 2970401696, 11482513428, 44491881033, 172766765654, 672186650116, 2619996250930, 10228902882021, 39996345469572, 156612023354364, 614044364443761 (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..28.

Ed Pegg, Jr., Illustrations of polyforms

Eric Weisstein's World of Mathematics, Polyrhomb

Eric Weisstein's World of Mathematics, Polyrect

Wikipedia, Polyomino

FORMULA

a(n) = 4*A006749(n) + 2*A006746(n) + 2*A006748(n) + 4*A006747(n) + 2*A056877(n) + 2*A056878(n) + 2*A144553(n) + A142886(n). - Andrew Howroyd, Dec 04 2018

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,changed

AUTHOR

Ed Pegg Jr, May 13 2009

EXTENSIONS

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

a(19)-a(28) from Andrew Howroyd, Dec 04 2018

STATUS

approved

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Last modified December 14 16:48 EST 2018. Contains 318098 sequences. (Running on oeis4.)