A047773 Number of dissectable polyhedra with n tetrahedral cells and symmetry of type D.
0, 0, 0, 1, 0, 0, 1, 1, 0, 2, 3, 0, 3, 5, 0, 7, 11, 0, 12, 23, 0, 30, 55, 0, 55, 114, 0, 143, 272, 0, 273, 588, 0, 728, 1428, 0, 1428, 3156, 0, 3876, 7750, 0, 7752, 17427, 0, 21318, 43263, 0, 43263, 98516, 0, 120175, 246672, 0, 246675, 567281, 0
Offset: 1
Keywords
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 A047773 examples
Crossrefs
Programs
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Mathematica
Table[Switch[Mod[n,6],1,If[1==n,0,3Binomial[(n-1)/2,(n-1)/6]/(n+2)],2,6Binomial[n/2,(n-2)/6]/(n+4)-3Binomial[(n-2)/2,(n-2)/6]/(2n+2)-If[2==Mod[n,12],3Binomial[(n-2)/4,(n-2)/12],6Binomial[(n-4)/4,(n-8)/12]]/(n+4),4,6Binomial[(n-2)/2,(n-4)/6]/(n+2),5,3Binomial[(n+1)/2,(n+1)/6]/(n+4)-Switch[Mod[n,24],5,12Binomial[(n-5)/8,(n-5)/24],17,24Binomial[(n-9)/8,(n-17)/24],,0]/(n+7),,0],{n,60}] (* Robert A. Russell, Mar 23 2024 *)
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PARI
/* here U=A047749, V=A047750, K=A047751, and Q=A047764 */ U(n)={if(n%2,my(m=(n-1)/2);(3*m+1)!/((m+1)!*(2*m+1)!),my(m=n/2);(3*m)!/(m!*(2*m+1)!))}; V(n)={if(n%2,my(m=(n-1)/2);6*(3*m+2)!/(m!*(2*m+3)!),my(m=n/2);(3*m)!*(5*m+1)/((m+1)!*(2*m+1)!))}; K(n)={if(n==1,1,if(n<5,0,if(n%12==5,U((n-5)/12),0)))}; Q(n)={if(n<8,0,if(n%6==2,U((n-2)/6),0))}; D(n)={if(n<3||n%3==0,0,if(n%3==1,U((n-1)/3),(1/2)*(V((n-2)/3)-2*K(n)-Q(n))))}; for(k=1,57,print1(D(k),", ")) \\ Hugo Pfoertner, Mar 07 2020
Formula
If n=3m+2 then (1/2)*(A047750(m) - 2*A047751(n) - A047764(n)), if n=3m+1 then A047749(m), otherwise 0.
G.f.: (G(z^6)-1)/z + z*G(z^6) - z + z^2*G(z^6)^2 + z^4*G(z^6)^2 - z^5*G(z^24) - z^17*G(z^24)^2 - (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 23 2024
Comments