A056638 Number of polygons of length 2n with two (self-avoiding polygon) holes on square lattice (not allowing rotations).

2, 122, 3400, 64210, 959742, 12294090, 141329502, 1500596864, 14998956452, 143004562082, 1312929589140, 11688960621918, 101451353794222, 861927965928610, 7191518458613614, 59078731187602024

Offset

12,1

Links

I. Jensen, Table of n, a(n) for n = 12..43 (from link below)

I. Jensen, More terms

Crossrefs

Cf. A002931.

Sequence in context: A217023 A332112 A074490 * A222873 A325889 A013475

Adjacent sequences: A056635 A056636 A056637 * A056639 A056640 A056641

Keyword

nonn

Author

N. J. A. Sloane, Aug 30 2000

Status

approved