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A057725 Number of "polyares" of order n (turning over not allowed). 1
1, 4, 16, 77, 351, 1747, 8745, 44724 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

An n-are is a shape formed from an n-celled polyomino by removing half of each square cell in such a way that at least half of the original join between cells is retained.

REFERENCES

Enumeration attributed by Andrew Clarke to Brendan Owen.

LINKS

Table of n, a(n) for n=1..8.

Andrew Clarke, Polyares

Andrew Clarke, Picture from Andrew Clarke's page showing the 9 polyares of order 3 when turning over is allowed.

Eric Weisstein's World of Mathematics, Polyare

CROSSREFS

Cf. A057724, A000105.

Sequence in context: A255906 A260949 A049426 * A196192 A159926 A020051

Adjacent sequences:  A057722 A057723 A057724 * A057726 A057727 A057728

KEYWORD

nonn,nice,more

AUTHOR

N. J. A. Sloane, Oct 29 2000

EXTENSIONS

Link updated by William Rex Marshall, Dec 16 2009

STATUS

approved

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Last modified January 24 04:35 EST 2020. Contains 331183 sequences. (Running on oeis4.)