A047765 - OEIS

%I #19 Apr 27 2024 03:37:11

%S 0,0,0,1,0,2,0,2,0,7,0,12,0,29,0,55,0,143,0,271,0,728,0,1428,0,3873,0,

%T 7752,0,21318,0,43256,0,120175,0,246675,0,690678,0,1430715,0,4032015,

%U 0,8414610,0,23841480,0,50067108,0,142498637,0,300830572

%N Number of dissectable polyhedra with n tetrahedral cells and symmetry of type P.

%C One of 17 different symmetry types comprising A007173 and A027610 and one of 10 for A371351. Also the number of tetrahedral clusters or polyominoes of the regular tiling with Schläfli symbol {3,3,oo}, both having type P achiral symmetry and n tetrahedral cells. The center of symmetry is the altitude of a tetrahedral face (21); the order of the symmetry group is 4. An achiral polyomino is identical to its reflection. - _Robert A. Russell_, Mar 22 2024

%H L. W. Beineke and R. E. Pippert, <a href="http://dx.doi.org/10.4153/CJM-1974-006-x">Enumerating dissectable polyhedra by their automorphism groups</a>, Canad. J. Math., 26 (1974), 50-67.

%H Robert A. Russell, <a href="/A047765/a047765.txt">Mathematica Graphics3D program for A047765 examples</a>

%F If n=2m then A047749(m) - A047764(n), otherwise 0.

%F G.f.: G(z^4) + z^2*G(z^4)^2 - z^2*G(z^12) - z^8*G(z^12)^2, where G(z) = 1 + z*G(z)^3 is the g.f. for A001764. - _Robert A. Russell_, Mar 22 2024

%t Table[If[OddQ[n],0,If[OddQ[n/2],2Binomial[(3n-2)/4,(n-2)/4],Binomial[3n/4,n/4]]/(n/2+1)-Switch[Mod[n,12],2,6Binomial[(n-2)/4,(n-2)/12],8,12Binomial[(n-4)/4,(n-2)/6],_,0]/(n+4)],{n,52}] (* _Robert A. Russell_, Mar 22 2024 *)

%Y Cf. A047767.

%Y Cf. A007173 (oriented), A027610 (unoriented), A371351 (achiral), A001764 (rooted), A047749 (type U), A047764 (type Q).

%K nonn

%O 1,6

%A _N. J. A. Sloane_