cp's OEIS Frontend

A220559 Number of ways to reciprocally link elements of an n X 5 array either to themselves or to exactly one horizontal or antidiagonal neighbor.

%I A220559 #7 Jul 31 2018 14:52:03
%S A220559 8,149,2604,45966,810778,14298089,252139015,4446314533,78407942556,
%T A220559 1382674335890,24382584703194,429971411669361,7582273047532603,
%U A220559 133708574584054949,2357865880743076540,41579468847568886038
%N A220559 Number of ways to reciprocally link elements of an n X 5 array either to themselves or to exactly one horizontal or antidiagonal neighbor.
%C A220559 Column 5 of A220562.
%H A220559 R. H. Hardin, <a href="/A220559/b220559.txt">Table of n, a(n) for n = 1..210</a>
%F A220559 Empirical: a(n) = 21*a(n-1) - 62*a(n-2) + 47*a(n-3) - 5*a(n-4) for n>5.
%F A220559 Empirical g.f.: x*(8 - 19*x - 29*x^2 + 144*x^3 - 23*x^4) / ((1 - x)*(1 - 20*x + 42*x^2 - 5*x^3)). - _Colin Barker_, Jul 31 2018
%e A220559 Some solutions for n=3 0=self 3=ne 4=w 6=e 7=sw (reciprocal directions total 10):
%e A220559 ..0..0..0..6..4....0..0..0..6..4....0..0..0..6..4....0..0..6..4..0
%e A220559 ..6..4..0..6..4....0..6..4..0..0....0..6..4..7..0....0..7..7..7..0
%e A220559 ..0..6..4..0..0....0..6..4..0..0....0..0..3..0..0....3..3..3..0..0
%Y A220559 Cf. A220562.
%K A220559 nonn
%O A220559 1,1
%A A220559 _R. H. Hardin_, Dec 16 2012