A223252 - OEIS

A223252

Two-loop graph coloring a rectangular array: number of nX5 0..4 arrays where 0..4 label nodes of a graph with edges 0,1 1,2 2,0 0,3 3,4 4,0 and every array movement to a horizontal or vertical neighbor moves along an edge of this graph

%I #4 Mar 18 2013 21:13:53

%S 208,4908,166892,5359892,200258884,6581646956,247417877452,

%T 8146965446276,306270743418628,10089859264898796,379171102402141516,

%U 12496512099428874724,469428050069027239844,15477220252232343414028

%N Two-loop graph coloring a rectangular array: number of nX5 0..4 arrays where 0..4 label nodes of a graph with edges 0,1 1,2 2,0 0,3 3,4 4,0 and every array movement to a horizontal or vertical neighbor moves along an edge of this graph

%C Column 5 of A223255

%H R. H. Hardin, <a href="/A223252/b223252.txt">Table of n, a(n) for n = 1..210</a>

%F Empirical: a(n) = 7*a(n-1) +1287*a(n-2) -8754*a(n-3) -66498*a(n-4) +293943*a(n-5) +1110271*a(n-6) -2420678*a(n-7) -6380827*a(n-8) +7393360*a(n-9) +14420088*a(n-10) -8685630*a(n-11) -12202500*a(n-12) +3405276*a(n-13) +3205824*a(n-14) -279936*a(n-15) -165888*a(n-16)

%e Some solutions for n=3

%e ..1..0..4..0..4....1..2..0..1..0....0..1..0..3..4....1..0..3..0..3

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

%e ..4..0..2..0..4....0..2..0..2..0....0..1..0..2..0....1..0..1..0..1

%K nonn

%O 1,1

%A _R. H. Hardin_ Mar 18 2013