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”).

Number of deltahedra with 2*n faces.
0

%I #17 Dec 23 2024 14:53:46

%S 1,1,2,5,13,47

%N Number of deltahedra with 2*n faces.

%C 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/.

%C [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.]

%H Antreas Hatzipolakis, <a href="https://web.archive.org/web/*/http://list.seqfan.eu/pipermail/seqfan/2023-January/074268.html">Number of Deltahedra</a>, SeqFan Mailing List, Jan 29 2023.

%H Mathematics Stack Exchange, <a href="https://math.stackexchange.com/questions/3537381/counting-deltahedra-with-2n-faces">Counting deltahedra with 2n faces</a>.

%H Allan Turton, <a href="https://geometry.pre-college.narkive.com/JIBdcdER/concave-deltahedra-with-less-than-12-faces">Concave deltahedra with less than 12 faces</a>, NK, geometry.pre-college, 2006.

%K nonn,more,changed

%O 2,3

%A _N. J. A. Sloane_, Feb 27 2023