cp's OEIS Frontend

A220560 Number of ways to reciprocally link elements of an nX6 array either to themselves or to exactly one horizontal or antidiagonal neighbor.

%I A220560 #6 Jul 23 2025 01:13:22
%S A220560 13,481,16310,561636,19333688,665748170,22926570957,789539775889,
%T A220560 27190037181789,936366170726784,32246430390993213,1110497486239608510,
%U A220560 38243137393453789704,1317011137774021018880,45355021979509463823738
%N A220560 Number of ways to reciprocally link elements of an nX6 array either to themselves or to exactly one horizontal or antidiagonal neighbor.
%C A220560 Column 6 of A220562
%H A220560 R. H. Hardin, <a href="/A220560/b220560.txt">Table of n, a(n) for n = 1..210</a>
%F A220560 Empirical: a(n) = 43*a(n-1) -317*a(n-2) +783*a(n-3) -721*a(n-4) +375*a(n-5) -125*a(n-6) +19*a(n-7) -a(n-8) for n>9
%e A220560 Some solutions for n=3 0=self 3=ne 4=w 6=e 7=sw (reciprocal directions total 10)
%e A220560 ..0..7..6..4..0..0....6..4..6..4..6..4....0..0..0..7..0..0....0..0..0..7..0..7
%e A220560 ..3..0..7..0..6..4....0..0..0..0..7..0....0..7..3..7..6..4....6..4..3..0..3..0
%e A220560 ..0..3..0..6..4..0....6..4..0..3..0..0....3..0..3..0..6..4....0..0..0..0..0..0
%K A220560 nonn
%O A220560 1,1
%A A220560 _R. H. Hardin_ Dec 16 2012