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Number of staircase polygons of area n with 2 (staircase polygon) holes on square lattice (not allowing rotations).
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%I #11 Jul 19 2014 09:29:47

%S 2,10,53,220,845,2975,9936,31640,97283,290173,844729,2408213,6746197,

%T 18613290,50688554,136464665,363724034,960862781,2518380075,

%U 6554072749,16949040877,43580221577,111475092069,283799832989

%N Number of staircase polygons of area n with 2 (staircase polygon) holes on square lattice (not allowing rotations).

%H I. Jensen, <a href="/A057415/b057415.txt">Table of n, a(n) for n = 13..86</a> (from link below)

%H I. Jensen, <a href="http://www.ms.unimelb.edu.au/~iwan/polygons/series/staircase.area.2hole.ser">More terms</a>

%K nonn

%O 13,1

%A _N. J. A. Sloane_, Aug 30 2000