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

Author

N. J. A. Sloane, Aug 30 2000

Keywords

• nonn

Links

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

Crossrefs

Cf. A002931.