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A223460 6X6X6 triangular graph without horizontal edges coloring a rectangular array: number of nX1 0..20 arrays where 0..20 label nodes of a graph with edges 0,1 0,2 1,3 1,4 2,4 2,5 3,6 3,7 4,7 4,8 5,8 5,9 6,10 6,11 7,11 7,12 8,12 8,13 9,13 9,14 10,15 10,16 11,16 11,17 12,17 12,18 13,18 13,19 14,19 14,20 and every array movement to a horizontal or vertical neighbor moves along an edge of this graph 1
21, 60, 190, 600, 1946, 6264, 20440, 66208, 216452, 702768, 2298936, 7470944, 24444168, 79466336, 260022112, 845441152, 2766427344, 8995380672, 29434608608, 95712808320, 313191301792, 1018418848640, 3332470833536, 10836405217792 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Column 1 of A223467

LINKS

R. H. Hardin, Table of n, a(n) for n = 1..210

FORMULA

Empirical: a(n) = 20*a(n-2) -126*a(n-4) +304*a(n-6) -252*a(n-8) +80*a(n-10) -8*a(n-12)

EXAMPLE

Some solutions for n=3

..1...15...11....1...11....6...12....7....4....4....8....9....1....2....7...13

..0...10....7....3...16...11...18...11....8....8....5....5....3....4....4...19

..2...15...11....6...10....6...13....7...12....5....9....9....1....8....2...14

CROSSREFS

Sequence in context: A037305 A223467 A051873 * A219690 A325319 A069133

Adjacent sequences:  A223457 A223458 A223459 * A223461 A223462 A223463

KEYWORD

nonn

AUTHOR

R. H. Hardin Mar 20 2013

STATUS

approved

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Last modified November 20 20:28 EST 2019. Contains 329347 sequences. (Running on oeis4.)