A057712 Number of "polyhes" of order n: a polyhe of order n is obtained by taking a polyhex made of n hexagons (A000228); cutting each of the n hexagons along a diameter and throwing away half that hexagon, in such a way that the remaining figure (made of n half-hexagons) is connected.

1, 4, 13, 60, 276, 1416, 7201, 37972, 201989, 1089815, 5929666, 32533673, 179657435

Offset

1,2

References

Enumeration of a(1)-a(8) attributed by Andrew Clarke to Brendan Owen.

Links

Table of n, a(n) for n=1..13.

Abaroth's World, Polyhes, Polyhalfhexes & Polytriamonds

Andrew Clarke, Polyhes

Andrew Clarke, Picture showing triangle formed by combining polyhes of orders 1, 2 and 3.

Eric Weisstein's World of Mathematics, Polyhe

Crossrefs

Sequence in context: A149487 A372125 A320359 * A208592 A367888 A351933

Adjacent sequences: A057709 A057710 A057711 * A057713 A057714 A057715

Keyword

nonn,nice,hard,more

Author

N. J. A. Sloane, Oct 27 2000

Extensions

Link updated by William Rex Marshall, Dec 16 2009

a(9)-a(13) from Aaron N. Siegel, May 23 2022

Status

approved