cp's OEIS Frontend

A220546 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.

%I A220546 #8 Jul 23 2025 01:12:34
%S A220546 1,8,224,32173,21668208,69961268156,1077372801893440,
%T A220546 79222784184855853978,27809964251933826835780981,
%U A220546 46605836505704256743057461864323
%N A220546 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 A220546 Diagonal of A220553
%H A220546 R. H. Hardin, <a href="/A220546/b220546.txt">Table of n, a(n) for n = 1..12</a>
%e A220546 Some solutions for n=3 0=self 2=n 3=ne 4=w 6=e 7=sw 8=s (reciprocal directions total 10)
%e A220546 ..0..8..8....0..0..8....6..4..7....8..0..0....6..4..0....8..6..4....0..0..7
%e A220546 ..8..2..2....0..7..2....8..3..0....2..8..8....0..7..0....2..8..0....0..3..0
%e A220546 ..2..0..0....3..0..0....2..0..0....0..2..2....3..6..4....0..2..0....0..6..4
%K A220546 nonn
%O A220546 1,2
%A A220546 _R. H. Hardin_ Dec 15 2012