A220617 - OEIS

%I #4 Dec 17 2012 04:36:41

%S 5,87,1189,17084,243119,3466455,49406943,704243629,10038098456,

%T 143080761421,2039439299333,29069688249415,414352491974681,

%U 5906082889319188,84183915242486395,1199937711608731991

%N Number of ways to reciprocally link elements of an nX4 array either to themselves or to exactly one horizontal, diagonal and antidiagonal neighbor

%C Column 4 of A220621

%H R. H. Hardin, <a href="/A220617/b220617.txt">Table of n, a(n) for n = 1..210</a>

%F Empirical: a(n) = 16*a(n-1) -18*a(n-2) -114*a(n-3) +230*a(n-4) -66*a(n-5) -78*a(n-6) +48*a(n-7) -4*a(n-8) -4*a(n-9) +a(n-10)

%e Some solutions for n=3 0=self 1=nw 3=ne 4=w 6=e 7=sw 9=se (reciprocal directions total 10)

%e ..0..9..6..4....0..0..6..4....0..6..4..0....9..7..0..0....9..7..0..0

%e ..0..7..1..0....0..0..0..0....0..0..0..7....3..1..6..4....3..1..6..4

%e ..3..0..0..0....0..0..6..4....0..0..3..0....0..0..0..0....0..6..4..0

%K nonn

%O 1,1

%A _R. H. Hardin_ Dec 17 2012