cp's OEIS Frontend

A220628 Number of ways to reciprocally link elements of an n X n array either to themselves or to exactly two horizontal or antidiagonal neighbors.

%I A220628 #7 Aug 15 2014 08:33:53
%S A220628 1,1,3,37,1481,183961,72097810,91163971015,374610359478958,
%T A220628 4999831941923800805,216409223358914018252290,
%U A220628 30357148112130816204187346595,13800400036239294148735727438211949
%N A220628 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 A220628 Diagonal of A220632.
%H A220628 R. H. Hardin, <a href="/A220628/b220628.txt">Table of n, a(n) for n = 1..16</a>
%e A220628 All solutions for n=3 0=self 3=ne 4=w 6=e 7=sw (reciprocal directions total 10)
%e A220628 .00.67.47...00.00.00...00.00.00
%e A220628 .36.34.00...00.67.47...00.00.00
%e A220628 .00.00.00...36.34.00...00.00.00
%K A220628 nonn
%O A220628 1,3
%A A220628 _R. H. Hardin_, Dec 17 2012