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Number of staircase polygons of area n with one (staircase polygon) hole on square lattice (not allowing rotations).
2

%I #11 Jul 19 2014 09:29:35

%S 1,4,18,62,205,624,1841,5214,14448,39118,104281,273900,711416,1828950,

%T 4663203,11801056,29677044,74209404,184655403,457446252,1128794669,

%U 2775534900,6802886782,16625602146,40524317635

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

%H I. Jensen, <a href="/A057414/b057414.txt">Table of n, a(n) for n = 8..113</a> (from link below)

%H I. Jensen, <a href="http://www.ms.unimelb.edu.au/~iwan/polygons/series/staircase.area.1hole.ser">More terms</a>

%K nonn

%O 8,2

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