A060637 Triangle T(n,k) (0 <= k <= n) giving number of tilings of the k-dimensional zonotope constructed from n vectors.

1, 2, 1, 4, 2, 1, 8, 6, 2, 1, 16, 24, 8, 2, 1, 32, 120, 62, 10, 2, 1, 64, 720, 908, 148, 12, 2, 1, 128, 5040, 24698, 7686, 338, 14, 2, 1, 256, 40320, 1232944

Offset: 0

Author

N. J. A. Sloane, Apr 16 2001

Keywords

• nonn
• tabl
• hard
• nice

Comments

The zonotope Z(n,k) is the projection of the n-dimensional hypercube onto the k-dimensional space and the tiles are the projections of the k-dimensional faces of the hypercube.

T(n,k) is also the number of signotopes on n elements of rank r=k+1. A signotope on n elements of rank r is a mapping X:{{1..n} choose r}->{+,-} such that for any r+1 indices I={i_0,...,i_r} with i_0 < i_1 < ... < i_r, the sequence X(I-i_0), X(I-i_1), ..., X(I-i_r) changes its sign at most once (see Felsner-Weil reference). - Manfred Scheucher, Feb 09 2022

Examples

			Triangle T(n,k) begins:
    1;
    2,    1;
    4,    2,     1;
    8,    6,     2,    1;
   16,   24,     8,    2,   1;
   32,  120,    62,   10,   2,  1;
   64,  720,   908,  148,  12,  2, 1;
  128, 5040, 24698, 7686, 338, 14, 2, 1;
  ...
		

References

• A. Bjorner, M. Las Vergnas, B. Sturmfels, N. White and G. M. Ziegler, Oriented Matroids, Encyclopedia of Mathematics 46, Second Edition, Cambridge University Press, 1999
• Victor Reiner, The generalized Baues problem, in New Perspectives in Algebraic Combinatorics (Berkeley, CA, 1996-1997), 293-336, Math. Sci. Res. Inst. Publ., 38, Cambridge Univ. Press, Cambridge, 1999.

Links

• N. Destainville, R. Mosseri and F. Bailly, Fixed-boundary octagonal random tilings: a combinatorial approach, arXiv:cond-mat/0004145 [cond-mat.stat-mech], 2000.
• N. Destainville, R. Mosseri and F. Bailly, Fixed-boundary octagonal random tilings: a combinatorial approach, Journal of Statistical Physics, 102 (2001), no. 1-2, 147-190.
• S. Felsner and H. Weil, Sweeps, arrangements and signotopes, Discrete Applied Mathematics, Volume 109, Issues 1-2, 2001, Pages 67-94.
• M. Latapy, Generalized Integer Partitions, Tilings of Zonotopes and Lattices, arXiv:math/0008022 [math.CO], 2000.

Crossrefs

Diagonals give A000079, A000142, A006245, A060595-A060602, A351383, A351384. Cf. A060638.

Extensions

Edited by Manfred Scheucher, Mar 08 2022