cp's OEIS Frontend

A220682 Number of ways to reciprocally link elements of an n X n array either to themselves or to exactly two horizontal, vertical or antidiagonal neighbors.

%I A220682 #7 Jul 23 2025 01:21:33
%S A220682 1,4,94,15452,15978924,107713940118,4701615485821782,
%T A220682 1328565529272722924682,2429341045430456043662317796
%N A220682 Number of ways to reciprocally link elements of an n X n array either to themselves or to exactly two horizontal, vertical or antidiagonal neighbors.
%C A220682 Diagonal of A220688
%e A220682 Some solutions for n=3 0=self 2=n 3=ne 4=w 6=e 7=sw 8=s (reciprocal directions total 10)
%e A220682 .68.48.78...00.68.48...00.00.00...00.00.78...00.67.48...68.47.78...00.68.48
%e A220682 .28.23.28...00.26.24...00.78.00...00.36.24...38.00.27...23.37.28...68.24.28
%e A220682 .26.46.24...00.00.00...36.24.00...00.00.00...26.34.00...36.46.24...26.46.24
%K A220682 nonn
%O A220682 1,2
%A A220682 _R. H. Hardin_ Dec 17 2012