A220612 - OEIS

%I #4 Dec 17 2012 04:18:49

%S 1,13,43,281,1277,7041,34981,183920,937663,4861869,24977087,128971605,

%T 664092737,3424806465,17647051243,90973240309,468858278192,

%U 2416753993341,12456282450653,64204249763017,330924094972255,1705685462529549

%N Number of ways to reciprocally link elements of an nX6 array either to themselves or to exactly two horizontal and vertical neighbors, without consecutive collinear links

%C Column 6 of A220614

%H R. H. Hardin, <a href="/A220612/b220612.txt">Table of n, a(n) for n = 1..210</a>

%F Empirical: a(n) = 3*a(n-1) +23*a(n-2) -40*a(n-3) -160*a(n-4) +190*a(n-5) +441*a(n-6) -369*a(n-7) -513*a(n-8) +278*a(n-9) +240*a(n-10) -64*a(n-11) -39*a(n-12) +3*a(n-13) +a(n-14)

%e Some solutions for n=3 0=self 2=n 4=w 6=e 8=s (reciprocal directions total 10)

%e .68.48.00.00.00.00...00.00.00.68.48.00...68.48.68.48.00.00...68.48.68.48.68.48

%e .26.24.00.00.68.48...00.00.00.26.24.00...26.24.26.24.68.48...26.24.26.24.26.24

%e .00.00.00.00.26.24...00.00.00.00.00.00...00.00.00.00.26.24...00.00.00.00.00.00

%K nonn

%O 1,2

%A _R. H. Hardin_ Dec 17 2012