cp's OEIS Frontend

A220686 Number of ways to reciprocally link elements of an nX6 array either to themselves or to exactly two horizontal, vertical or antidiagonal neighbors.

%I A220686 #6 Jul 23 2025 01:21:55
%S A220686 1,351,46027,6349886,822649205,107713940118,14108684022136,
%T A220686 1848014307847883,242044667782801540,31702119421997470360,
%U A220686 4152232349834304063419,543844751860183504221026
%N A220686 Number of ways to reciprocally link elements of an nX6 array either to themselves or to exactly two horizontal, vertical or antidiagonal neighbors.
%C A220686 Column 6 of A220688
%H A220686 R. H. Hardin, <a href="/A220686/b220686.txt">Table of n, a(n) for n = 1..210</a>
%e A220686 Some solutions for n=3 0=self 2=n 3=ne 4=w 6=e 7=sw 8=s (reciprocal directions total 10)
%e A220686 .00.67.46.46.46.48...00.00.68.48.00.00...00.67.46.46.46.48...68.46.47.68.46.48
%e A220686 .38.67.46.47.78.28...00.00.26.24.68.47...36.46.47.00.67.24...26.34.00.26.48.27
%e A220686 .23.00.36.34.26.24...00.00.00.00.23.00...00.36.46.34.00.00...00.00.00.00.23.00
%K A220686 nonn
%O A220686 1,2
%A A220686 _R. H. Hardin_ Dec 17 2012