A371350 - OEIS

A371350

Number of chiral pairs of polyominoes composed of n tetrahedral cells of the hyperbolic regular tiling with Schläfli symbol {3,3,oo}.

0, 0, 0, 1, 3, 16, 78, 397, 2037, 10820, 58349, 320824, 1790189, 10125858, 57938771, 334941363, 1953830203, 11489589280, 68053757016, 405714603234, 2433001205088, 14668531344984, 88869454457853, 540834122500464

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OFFSET

1,5

COMMENTS

Also number of chiral pairs of simplicial 3-clusters or stack polytopes with n tetrahedral cells. Each member of a chiral pair is a reflection but not a rotation of the other.

LINKS

Table of n, a(n) for n=1..24.

L. W. Beineke and R. E. Pippert Enumerating dissectable polyhedra by their automorphism groups, Can. J. Math., 26 (1974), 50-67

F. Hering et al., The enumeration of stack polytopes and simplicial clusters, Discrete Math., 40 (1982), 203-217.

FORMULA

a(n) = A007173(n) - A027610(n) = (A007173(n) - A371351(n))/2 = A027610(n) - A371351(n).

a(n) = h(3,n) - H(3,n) in Table 8 of Hering link.

G.f.: (4*G(z) - 2*G(z)^2 + z*G(z)^4 - 2*G(z^2) - 3z*G(z^2)^2 + 2z*(4 G(z^3) + 2z*G(z^3)^2 - 3*G(z^4) - 2z*G(z^6))) / 24.

MATHEMATICA

Table[Switch[Mod[n, 3], 1, Binomial[n, (n-1)/3], 2, Binomial[n, (n-2)/3], _, 0]/(3n)+(Binomial[3n, n]/(6n+3)-If[OddQ[n], Binomial[3(n-1)/2+1, n], Binomial[3n/2, n]/3]-2If[1==Mod[n, 4], Binomial[(3n-3)/4, (n-1)/2], 0]-2If[2==Mod[n, 6], Binomial[n/2-1, n/3-2/3], 0])/(4n+4), {n, 30}]

CROSSREFS

Sum of chiral symmetry types (A047776, A047774, A047762, A047758, A047752, A047769, A047766 [type O]) in Beineke article.

Cf. A007173 (oriented), A027610 (oriented), A371351 (achiral), A001764 (rooted), A369314 {3,oo}, A369474 {3,3,3,oo}.

Sequence in context: A005386 A053572 A329806 * A309915 A343117 A055842

Adjacent sequences: A371347 A371348 A371349 * A371351 A371352 A371353

KEYWORD

nonn

AUTHOR

Robert A. Russell, Mar 19 2024

STATUS

approved