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%I #28 Sep 29 2023 19:34:08
%S 1,1,2,7,39
%N Number of nonisomorphic polytetrahedra with n identical regular tetrahedra connected face-to-face or edge-to-edge (chiral shapes counted twice).
%C Polytetrahedra are a 3-dimensional generalization of polyiamonds, composed of unit regular tetrahedra in Euclidean 3-space. - _Peter Kagey_, Aug 05 2019, adapted from comment by _Jonathan Vos Post_.
%H Andrew I. Campbell, Valerie J. Anderson, Jeroen S. van Duijneveldt and Paul Bartlett, <a href="https://www.researchgate.net/publication/7670647_Dynamical_Arrest_in_Attractive_Colloids_The_Effect_of_Long-Range_Repulsion">Dynamical Arrest in Attractive Colloids: The Effect of Long-Range Repulsion</a>, Phys. Rev. Lett. 94, 208301 (2005).
%H Peter Kagey, <a href="/A119602/a119602.pdf">Examples of the seven shapes that can be constructed from three tetrahedra</a>, with Mathematica code.
%H J. F. Sadoc, <a href="https://doi.org/10.1007/s100510051009">Boerdijk-Coxeter helix and biological helices</a>, Eur. Phys. J. B 12, 309-318.
%H Jonathan Vos Post, <a href="/A119602/a119602.txt">Original example for entry</a>.
%H Eric Weisstein et al., <a href="http://mathworld.wolfram.com/Tetrahedron.html">Tetrahedron</a>.
%H Wikipedia, <a href="http://en.wikipedia.org/wiki/Polyiamond">Polyiamond</a>
%H Wikipedia, <a href="https://en.wikipedia.org/wiki/Deltahedron">Deltahedron</a>
%e For n = 1, the a(1) = 1 polytetrahedron is the tetrahedron itself.
%e For n = 2, the a(2) = 2 polytetrahedra are formed by either gluing two tetrahedra along a face (triangular bipyramid) or gluing two tetrahedra along an edge.
%e For n = 7, the a(3) = 7 polytetrahedra are given in the links section.
%Y Cf. A000577, A000105.
%K nonn,more
%O 0,3
%A _Jonathan Vos Post_, Jun 02 2006
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