A057785 Erroneous version of A355562.

0, 1, 2, 1, 1, 4, 4, 10, 13, 31, 43, 102

Offset

1,3

Comments

It would be nice to have a definition of "polypon"! - N. J. A. Sloane, May 09 2007

By looking at the Clarke pictures, I guess that the unit element is a triangle with internal angles of 120 degrees and two of 30 degrees. The polypons are connected, nonoverlapping assemblies of these, where connectivity is defined via common sides; a common point is not enough. Only non-congruential assemblies are counted, those which cannot be mapped onto each other by rotations, translations or mirrors along a line or point. However, the polypons are not all of these, because some of the free-form assemblies of this kind would need placement of the unit that violates the format by the grid. (The first case where this happens is with assemblies of 3 units: the picture shows 2 examples with assemblies of 3 units, but I can imagine at least 1 more where the unit would need to hide/cover one of the grid's edges.) - R. J. Mathar, Dec 10 2007

References

Computed by Brendan Owen.

Links

Table of n, a(n) for n=1..12.

Andrew Clarke, Other Polyforms

Crossrefs

Cf. A057784, A057786, A355562 (corrected version).

Sequence in context: A177263 A357050 A197380 * A305882 A339285 A363043

Adjacent sequences: A057782 A057783 A057784 * A057786 A057787 A057788

Keyword

dead

Author

N. J. A. Sloane, Nov 04 2000

Extensions

Link updated by William Rex Marshall, Dec 16 2009

Status

approved