%I
%S 1,1,3,13,107,1617,44976,2282408,216083336,37166744488,11934907610044,
%T 6974153590170208,7595477025017870022,15083748097547577433271,
%U 55729708477784939752304144,376141278066033748724918163244
%N Number of ways to reciprocally link elements of an n X n array either to themselves or to exactly two horizontal and antidiagonal neighbors, without consecutive collinear links
%C Diagonal of A220708
%H R. H. Hardin, <a href="/A220704/b220704.txt">Table of n, a(n) for n = 1..18</a>
%e All solutions for n=3 0=self 3=ne 4=w 6=e 7=sw (reciprocal directions total 10)
%e .00.00.00...00.67.47...00.00.00
%e .00.00.00...36.34.00...00.67.47
%e .00.00.00...00.00.00...36.34.00
%K nonn
%O 1,3
%A _R. H. Hardin_ Dec 18 2012
