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A057411 Number of staircase polygons of perimeter 2n with 2 (staircase polygon) holes on square lattice (not allowing rotations). 1
2, 54, 737, 7330, 60362, 438284, 2908069, 18032906, 106088843, 598428100, 3261717223, 17278076588, 89351738840, 452686823796, 2253216812878, 11043624323310, 53399946187312, 255135202590382, 1206067676613670 (list; graph; refs; listen; history; text; internal format)
OFFSET

12,1

LINKS

I. Jensen, Table of n, a(n) for n = 12..75 (from link below)

I. Jensen, More terms

CROSSREFS

Sequence in context: A200195 A202739 A055024 * A157058 A071798 A123686

Adjacent sequences:  A057408 A057409 A057410 * A057412 A057413 A057414

KEYWORD

nonn

AUTHOR

N. J. A. Sloane, Aug 30 2000

STATUS

approved

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Last modified October 20 17:15 EDT 2014. Contains 248351 sequences.