A220546 - OEIS

%I #6 Dec 18 2015 18:18:23

%S 1,8,224,32173,21668208,69961268156,1077372801893440,

%T 79222784184855853978,27809964251933826835780981,

%U 46605836505704256743057461864323

%N Number of ways to reciprocally link elements of an n X n array either to themselves or to exactly one horizontal, vertical or antidiagonal neighbor

%C Diagonal of A220553

%H R. H. Hardin, <a href="/A220546/b220546.txt">Table of n, a(n) for n = 1..12</a>

%e Some solutions for n=3 0=self 2=n 3=ne 4=w 6=e 7=sw 8=s (reciprocal directions total 10)

%e ..0..8..8....0..0..8....6..4..7....8..0..0....6..4..0....8..6..4....0..0..7

%e ..8..2..2....0..7..2....8..3..0....2..8..8....0..7..0....2..8..0....0..3..0

%e ..2..0..0....3..0..0....2..0..0....0..2..2....3..6..4....0..2..0....0..6..4

%K nonn

%O 1,2

%A _R. H. Hardin_ Dec 15 2012