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A056638
Number of polygons of length 2n with two (self-avoiding polygon) holes on square lattice (not allowing rotations).
2
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
KEYWORD
nonn
AUTHOR
N. J. A. Sloane, Aug 30 2000
STATUS
approved