A057725 Number of "polyares" of order n (turning over not allowed).

1, 4, 16, 77, 351, 1747, 8745, 44724, 230765, 1203567, 6323074, 33444084, 177863517, 950557538, 5101540598

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..15.

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: A260949 A049426 A345889 * A196192 A367261 A364474

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

a(9)-a(11) from Sean A. Irvine, Jul 02 2022

a(12)-a(15) from John Mason, Mar 19 2023

Status

approved