cp's OEIS Frontend

A220596 Number of ways to reciprocally link elements of an n X n array either to themselves or to exactly two horizontal, vertical and antidiagonal neighbors, without 3-loops.

%I A220596 #7 Jul 23 2025 01:16:49
%S A220596 1,2,65,9047,7558495,41011388731,1417058414112748,
%T A220596 305516864725171735943,412489181606705015322075070
%N A220596 Number of ways to reciprocally link elements of an n X n array either to themselves or to exactly two horizontal, vertical and antidiagonal neighbors, without 3-loops.
%C A220596 Diagonal of A220602
%e A220596 Some solutions for n=3 0=self 2=n 3=ne 4=w 6=e 7=sw 8=s (reciprocal directions total 10)
%e A220596 .00.00.00...00.78.78...68.46.47...68.46.48...00.67.48...00.78.00...00.67.47
%e A220596 .00.67.47...38.23.28...28.36.47...28.68.24...38.67.24...38.28.00...38.37.00
%e A220596 .36.34.00...26.46.24...26.34.00...26.24.00...23.00.00...26.24.00...23.00.00
%K A220596 nonn
%O A220596 1,2
%A A220596 _R. H. Hardin_ Dec 16 2012