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A223339
5X5X5 triangular graph coloring a rectangular array: number of nX3 0..14 arrays where 0..14 label nodes of a graph with edges 0,1 0,2 1,2 1,3 1,4 2,4 3,4 2,5 4,5 3,6 3,7 4,7 6,7 4,8 5,8 7,8 5,9 8,9 6,10 6,11 7,11 10,11 7,12 8,12 11,12 11,12 8,13 9,13 12,13 9,14 13,14 and every array movement to a horizontal or vertical neighbor moves along an edge of this graph
1
264, 6696, 190740, 5514360, 161370036, 4730218284, 138947808456, 4081817304888, 119957730775764, 3525232400391672, 103605465347776488, 3044880491450389068, 89488169170132234404, 2630017284676266897204, 77295354555176007541020
OFFSET
1,1
COMMENTS
Column 3 of A223344
LINKS
FORMULA
Empirical: a(n) = 18*a(n-1) +585*a(n-2) -5160*a(n-3) -85485*a(n-4) +505600*a(n-5) +3996404*a(n-6) -19237700*a(n-7) -89239938*a(n-8) +375211256*a(n-9) +1104726794*a(n-10) -4232791939*a(n-11) -8081655126*a(n-12) +29153658888*a(n-13) +35808212649*a(n-14) -125320594701*a(n-15) -95870415823*a(n-16) +336725591045*a(n-17) +149825017362*a(n-18) -554412838812*a(n-19) -124734888118*a(n-20) +531808961051*a(n-21) +43836491896*a(n-22) -268190168640*a(n-23) -2736660827*a(n-24) +57764829598*a(n-25) +504580148*a(n-26) -3286957664*a(n-27) +156627216*a(n-28) +43946272*a(n-29) -3289536*a(n-30)
EXAMPLE
Some solutions for n=3
..7..4..3....3..7.12...11.12.11....1..3..4....7.12..7....7.11.12....7..8..5
..3..7..4....7..6..7...10.11..6....2..4..1...12..7..3....8.12.11....6..7..8
..7..4..2...12.11..6...11.12.11....4..2..4....7.12..7....7..8..7....3..6..7
CROSSREFS
Sequence in context: A092724 A112069 A282781 * A022043 A035315 A288877
KEYWORD
nonn
AUTHOR
R. H. Hardin Mar 19 2013
STATUS
approved