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A056780 Rectangular polyominoes: number of n-celled polyominoes when the cell is a rectangle. 4
1, 2, 3, 9, 21, 68, 208, 730, 2542, 9287, 34053, 127112, 476849, 1803636, 6851960, 26157362, 100211446, 385239872 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

LINKS

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

Ed Pegg, Jr., Illustrations of polyforms

M. Vicher, Polyforms

M. Vicher, The 21 5-celled rectangular polyominoes

M. Vicher, The 21 5-celled rectangular polyominoes

Eric Weisstein's World of Mathematics, Polyrect [From Eric W. Weisstein, Apr 24 2009]

CROSSREFS

Sequence in context: A101531 A099607 A077550 * A141505 A111360 A111238

Adjacent sequences:  A056777 A056778 A056779 * A056781 A056782 A056783

KEYWORD

nice,nonn,hard,more

AUTHOR

James A. Sellers, Aug 28 2000

EXTENSIONS

Edited by N. J. A. Sloane, Apr 25, 2001

Two more terms from Ed Pegg Jr, May 13 2009

a(13)-a(18) from Joseph Myers, Nov 15 2010

STATUS

approved

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Last modified July 26 06:03 EDT 2017. Contains 289798 sequences.