%I #4 Dec 16 2012 05:50:24

%S 21,1544,101052,6743873,449429440,29955561052,1996515036228,

%T 133064181801048,8868465829053416,591065515195237024,

%U 39393331961841054032,2625486595153945514656,174983417444316851450400

%N Number of ways to reciprocally link elements of an nX7 array either to themselves or to exactly one horizontal or antidiagonal neighbor

%C Column 7 of A220562

%H R. H. Hardin, <a href="/A220561/b220561.txt">Table of n, a(n) for n = 1..210</a>

%F Empirical: a(n) = 85*a(n-1) -1330*a(n-2) +7350*a(n-3) -15316*a(n-4) +12720*a(n-5) -3168*a(n-6) for n>9

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

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

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

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

%K nonn

%O 1,1

%A _R. H. Hardin_ Dec 16 2012