login

Year-end appeal: Please make a donation to the OEIS Foundation to support ongoing development and maintenance of the OEIS. We are now in our 61st year, we have over 378,000 sequences, and we’ve reached 11,000 citations (which often say “discovered thanks to the OEIS”).

A144222
Floor of the volumes of the first sixteen Lobell polyhedra.
2
4, 6, 7, 9, 10, 11, 13, 14, 15, 17, 18, 19, 21, 22, 23, 24
OFFSET
5,1
COMMENTS
This article defines a pair of combinatorial operations on the combinatorial structure of compact right-angled hyperbolic polyhedra in dimension three called decomposition and edge surgery. It is shown that these operations simplify the combinatorics of such a polyhedron, while keeping it within the class of right-angled objects, until it is a disjoint union of Lobell polyhedra, a class of polyhedra which generalizes the dodecahedron. Furthermore, these combinatorial operations are shown to have geometric realizations which are volume decreasing. This allows for an organization of the volumes of right-angled hyperbolic polyhedra and allows, in particular, the determination of the polyhedra with smallest and second-smallest volumes.
FORMULA
a(n) = Floor[vol(L(n))].
EXAMPLE
n..|.vol(L(n))
==============
5..|.4.306....
6..|.6.023....
7..|.7.563....
8..|.9.019....
9..|10.426....
10.|11.801....
11.|13.156....
12.|14.494....
13.|15.822....
14.|17.140....
15.|18.452....
16.|19.758....
17.|21.059....
18.|22.356....
19.|23.651....
20.|24.943....
==============
CROSSREFS
Sequence in context: A001690 A105447 A242286 * A010414 A254122 A095096
KEYWORD
nonn
AUTHOR
Jonathan Vos Post, Sep 14 2008
EXTENSIONS
Replaced link to cached arXiv URL by the permanent version - R. J. Mathar, Mar 01 2010
STATUS
approved