A360513 Number of deltahedra with 2*n faces.

1, 1, 2, 5, 13, 47

Offset

2,3

Comments

The terms shown were found by Professor Keh-Ming Lu, Dept. of CSIE, Asia University, Taiwan. Two potentially relevant links are https://geometry.pre-college.narkive.com/JIBdcdER/concave-deltahedra-with-less-than-12-faces and https://www.kehminglu.com/books/.

[It would be nice if someone could look at these URLs and provide proper links. The sequence seems important enough to justify this less-than-perfect preliminary entry.]

Links

Table of n, a(n) for n=2..7.

Antreas Hatzipolakis, Number of Deltahedra, SeqFan Mailing List, Jan 29 2023.

Mathematics Stack Exchange, Counting deltahedra with 2n faces.

Allan Turton, Concave deltahedra with less than 12 faces, NK, geometry.pre-college, 2006.

Crossrefs

Sequence in context: A085632 A111563 A079573 * A194635 A212821 A067021

Adjacent sequences: A360510 A360511 A360512 * A360514 A360515 A360516

Keyword

nonn,more

Author

N. J. A. Sloane, Feb 27 2023

Status

approved