1,2

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

Enumeration attributed by Andrew Clarke to Brendan Owen.

Andrew Clarke's Polyares page

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

Cf. A057725, A000105.

Sequence in context: A109743 A139150 A113271 this_sequence A129879 A001427 A020128

Adjacent sequences: A057721 A057722 A057723 this_sequence A057725 A057726 A057727

nonn,nice

N. J. A. Sloane (njas(AT)research.att.com), Oct 29 2000