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A223423 T(n,k)=3-level binary fanout graph coloring a rectangular array: number of nXk 0..6 arrays where 0..6 label nodes of a graph with edges 0,1 1,3 1,4 0,2 2,5 2,6 and every array movement to a horizontal or vertical neighbor moves along an edge of this graph 8
7, 12, 12, 26, 40, 26, 48, 136, 136, 48, 104, 464, 868, 464, 104, 192, 1584, 4720, 4720, 1584, 192, 416, 5408, 29912, 47872, 29912, 5408, 416, 768, 18464, 163168, 486016, 486016, 163168, 18464, 768, 1664, 63040, 1033328, 4934272, 9210784, 4934272 (list; table; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Table starts

....7.....12........26..........48............104..............192

...12.....40.......136.........464...........1584.............5408

...26....136.......868........4720..........29912...........163168

...48....464......4720.......47872.........486016..........4934272

..104...1584.....29912......486016........9210784........150006016

..192...5408....163168.....4934272......150006016.......4565849088

..416..18464...1033328....50097024.....2844612736.....139114196992

..768..63040...5638336...508632832....46345527296....4240305623040

.1664.215232..35704800..5164146176...878977950208..129279082045440

.3072.734848.194827648.52431620096.14321836797952.3941937218551808

LINKS

R. H. Hardin, Table of n, a(n) for n = 1..544

FORMULA

Empirical for column k:

k=1: a(n) = 4*a(n-2) for n>3

k=2: a(n) = 4*a(n-1) -2*a(n-2)

k=3: a(n) = 38*a(n-2) -120*a(n-4) +32*a(n-6)

k=4: a(n) = 14*a(n-1) -36*a(n-2) -40*a(n-3) +88*a(n-4) +32*a(n-5) -32*a(n-6)

k=5: a(n) = 392*a(n-2) -26768*a(n-4) +353408*a(n-6) -1274624*a(n-8) +1441792*a(n-10) -307200*a(n-12) for n>13

k=6: [order 18]

k=7: [order 36]

EXAMPLE

Some solutions for n=3 k=4

..5..2..6..2....5..2..0..1....1..3..1..0....1..0..1..4....0..2..6..2

..2..0..2..6....2..6..2..0....3..1..4..1....4..1..4..1....1..0..2..0

..0..1..0..2....6..2..0..1....1..4..1..0....1..3..1..4....4..1..0..2

CROSSREFS

Column 2 is A056236(n+1)

Sequence in context: A180570 A074474 A070420 * A274334 A328414 A083681

Adjacent sequences:  A223420 A223421 A223422 * A223424 A223425 A223426

KEYWORD

nonn,tabl

AUTHOR

R. H. Hardin Mar 20 2013

STATUS

approved

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Last modified July 29 12:41 EDT 2021. Contains 346346 sequences. (Running on oeis4.)