A277741 Symmetric array read by antidiagonals: T(n,k) (n >= 1, k >= 1) = number of multiquadrangulations of the sphere with n stable equilibria and k unstable equilibria.

1, 1, 1, 1, 2, 1, 2, 5, 5, 2, 3, 13, 20, 13, 3, 6, 35, 83, 83, 35, 6, 12, 104, 340, 504, 340, 12, 27, 315, 1401, 2843, 2843, 1401, 316, 27, 65, 1021, 5809, 15578, 21420, 15578, 5809, 1021, 65

Offset

1,5

Links

Table of n, a(n) for n=1..44.

Richard Kapolnai, Gabor Domokos, and Timea Szabo, Generating spherical multiquadrangulations by restricted vertex splittings and the reducibility of equilibrium classes Periodica Polytechnica Electrical Engineering, 56(1):11-10, 2012. Also arXiv:1206.1698 [cs.DM], 2012. See Table 1.

Example

The array begins:
   1,    1,    1,     2,     3,     6,   12,   27, 65, ...
   1,    2,    5,    13,    35,   104,  315, 1021, ...
   1,    5,   20,    83,   340,  1401, 5809, ...
   2,   13,   83,   504,  2843, 15578, ...
   3,   35,  340,  2843, 21420, ...
   6,  104, 1401, 15578, ...
  12,  315, 5809, ...
  27, 1021, ...
  65, ...
  ...

Crossrefs

Row 2 (equally, column 2) is A006082.

Sequence in context: A143913 A228815 A241555 * A241138 A241349 A330405

Adjacent sequences: A277738 A277739 A277740 * A277742 A277743 A277744

Keyword

nonn,tabl,more

Author

N. J. A. Sloane, Nov 07 2016

Status

approved