login
Number of ways to reciprocally link elements of an n X n array either to themselves or to exactly two horizontal or antidiagonal neighbors.
1

%I #7 Aug 15 2014 08:33:53

%S 1,1,3,37,1481,183961,72097810,91163971015,374610359478958,

%T 4999831941923800805,216409223358914018252290,

%U 30357148112130816204187346595,13800400036239294148735727438211949

%N Number of ways to reciprocally link elements of an n X n array either to themselves or to exactly two horizontal or antidiagonal neighbors.

%C Diagonal of A220632.

%H R. H. Hardin, <a href="/A220628/b220628.txt">Table of n, a(n) for n = 1..16</a>

%e All solutions for n=3 0=self 3=ne 4=w 6=e 7=sw (reciprocal directions total 10)

%e .00.67.47...00.00.00...00.00.00

%e .36.34.00...00.67.47...00.00.00

%e .00.00.00...36.34.00...00.00.00

%K nonn

%O 1,3

%A _R. H. Hardin_, Dec 17 2012