cp's OEIS Frontend

A220630 Number of ways to reciprocally link elements of an nX6 array either to themselves or to exactly two horizontal or antidiagonal neighbors.

%I A220630 #6 Jul 23 2025 01:19:09
%S A220630 1,16,158,1665,17527,183961,1932695,20301254,213251377,2240062837,
%T A220630 23530357757,247170637157,2596361852466,27273040848960,
%U A220630 286485012144200,3009333012881404,31611026051882958,332052638832405598
%N A220630 Number of ways to reciprocally link elements of an nX6 array either to themselves or to exactly two horizontal or antidiagonal neighbors.
%C A220630 Column 6 of A220632
%H A220630 R. H. Hardin, <a href="/A220630/b220630.txt">Table of n, a(n) for n = 1..210</a>
%F A220630 Empirical: a(n) = 7*a(n-1) +31*a(n-2) +57*a(n-3) +43*a(n-4) -3*a(n-5) -36*a(n-6) +19*a(n-7) -6*a(n-8) +a(n-9)
%e A220630 Some solutions for n=3 0=self 3=ne 4=w 6=e 7=sw (reciprocal directions total 10)
%e A220630 .00.67.46.46.46.47...00.00.67.46.46.47...00.00.00.00.67.47...00.00.67.47.00.00
%e A220630 .36.46.47.00.37.00...00.36.46.47.37.00...00.00.00.36.34.00...00.37.37.67.46.47
%e A220630 .00.36.46.34.00.00...00.00.36.34.00.00...00.00.00.00.00.00...36.34.36.46.34.00
%K A220630 nonn
%O A220630 1,2
%A A220630 _R. H. Hardin_ Dec 17 2012