cp's OEIS Frontend

A220624 Number of ways to reciprocally link elements of an 5Xn array either to themselves or to exactly one horizontal, diagonal and antidiagonal neighbor.

%I A220624 #6 Jul 23 2025 01:18:48
%S A220624 1,228,4657,243119,8608738,356768525,13864972277,553125347136,
%T A220624 21831846871613,865461975018339,34247958158855874,1356237159188241529,
%U A220624 53691862459540232153,2125854494007156918632,84166119627538600335289
%N A220624 Number of ways to reciprocally link elements of an 5Xn array either to themselves or to exactly one horizontal, diagonal and antidiagonal neighbor.
%C A220624 Row 5 of A220621
%H A220624 R. H. Hardin, <a href="/A220624/b220624.txt">Table of n, a(n) for n = 1..210</a>
%F A220624 Empirical: a(n) = 29*a(n-1) +557*a(n-2) -4948*a(n-3) -24662*a(n-4) +187560*a(n-5) +182180*a(n-6) -1893504*a(n-7) -127344*a(n-8) +6325072*a(n-9) +132352*a(n-10) -7384448*a(n-11) -1323456*a(n-12) +2439808*a(n-13) +987648*a(n-14) -7168*a(n-15) -69632*a(n-16) +32768*a(n-17)
%e A220624 Some solutions for n=3 0=self 1=nw 3=ne 4=w 6=e 7=sw 9=se (reciprocal directions total 10)
%e A220624 ..9..0..0....0..7..0....6..4..0....0..7..0....0..6..4....0..0..7....0..6..4
%e A220624 ..0..1..0....3..7..0....0..0..0....3..7..0....0..9..0....0..3..0....0..7..0
%e A220624 ..6..4..7....3..6..4....0..6..4....3..6..4....0..0..1....0..9..0....3..7..0
%e A220624 ..9..3..0....0..7..7....0..6..4....6..4..0....6..4..0....6..4..1....3..0..0
%e A220624 ..0..1..0....3..3..0....0..6..4....6..4..0....0..0..0....0..6..4....6..4..0
%K A220624 nonn
%O A220624 1,2
%A A220624 _R. H. Hardin_ Dec 17 2012