A047766 Number of dissectable polyhedra with n tetrahedral cells with symmetry of type N or chiral pairs with symmetry of type O.

0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 5, 0, 0, 0, 0, 0, 26, 0, 0, 0, 0, 0, 133, 0, 0, 0, 0, 0, 708, 0, 0, 0, 0, 0, 3861, 0, 0, 0, 0, 0, 21604, 0, 0, 0, 0, 0, 123266, 0, 0, 0, 0, 0, 715221, 0, 0, 0, 0, 0, 4206956, 0, 0, 0, 0, 0, 25032840, 0, 0, 0, 0

Offset: 1

Author

N. J. A. Sloane

Keywords

• nonn

Comments

Two of 17 different symmetry types comprising A007173 and A027610. Type N is one of 10 for A371351; type O one of 7 for A371350. Also the number of tetrahedral clusters or polyominoes of the regular tiling with Schläfli symbol {3,3,oo}, both having type N achiral symmetry or type O chiral symmetry and n tetrahedral cells. The axis of threefold rotational symmetry is the altitude of a tetrahedron (32); the order of the symmetry group is 6. For type N, the two rooted polyominoes sharing the central face are a chiral pair reflected in that face; for type O they have the same orientation. - Robert A. Russell, Mar 22 2024

Links

• L. W. Beineke and R. E. Pippert, Enumerating dissectable polyhedra by their automorphism groups, Canad. J. Math., 26 (1974), 50-67.
• Robert A. Russell, Mathematica Graphics3D program for A047766 examples

Crossrefs

Cf. A047768.

Cf. A007173 (oriented), A027610 (unoriented), A371350 (chiral), A371351 (achiral), A001764 (rooted), A047764 (type Q).

Programs

Mathematica

Table[Switch[Mod[n,12],2,3Binomial[(n-2)/2,(n-2)/6]/(2n+2)-3Binomial[(n-2)/4,(n-2)/12]/(n+4),8,3Binomial[(n-2)/2,(n-2)/6]/(2n+2)-6Binomial[(n-4)/4,(n-2)/6]/(n+4),,0],{n,50}] (* _Robert A. Russell, Mar 22 2024 *)

Formula

If n=6m+2 then (1/2)*(A001764(m) - A047764(n)), otherwise 0.

G.f.: (z^2*G(z^6) - z^2*G(z^12) - z^8*G(z^12)^2) / 2, where G(z) = 1 + z*G(z)^3 is the g.f. for A001764. - Robert A. Russell, Mar 22 2024

Extensions

2nd A-number in the formula corrected by R. J. Mathar, Oct 21 2008