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A223396 4 X 4 square grid graph coloring a rectangular array: number of n X 2 0..15 arrays where 0..15 label nodes of the square grid graph and every array movement to a horizontal or vertical neighbor moves along an edge of this graph. 1
48, 328, 2360, 17280, 127464, 943016, 6985008, 51763176, 383669400, 2843977792, 21081830152, 156277203016, 1158470626096, 8587668090888, 63659878472312, 471907077858304, 3498220894515624, 25932117973637736, 192233359691316016 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Column 2 of A223402.

LINKS

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

FORMULA

Empirical: a(n) = 10*a(n-1) - 18*a(n-2) - 9*a(n-3) + 2*a(n-4).

Empirical g.f.: 8*x*(2 + x)*(3 - 11*x + 2*x^2) / (1 - 10*x + 18*x^2 + 9*x^3 - 2*x^4). - Colin Barker, Aug 20 2018

EXAMPLE

Some solutions for n=3:

..6.10...10.14...13.14....9.13....8..9....6..2....9..5....9.13....3..7....5..1

.10..6...14.10....9.10...13..9....4..8....7..3...13..9...10.14....2..6....4..5

.14.10...10.14...10.11....9.10....8..9...11..7....9..5...14.15....6..2....0..4

Vertex neighbors:

0 -> 1 4

1 -> 0 2 5

2 -> 1 3 6

3 -> 2 7

4 -> 0 5 8

5 -> 4 1 6 9

6 -> 5 2 7 10

7 -> 6 3 11

8 -> 4 9 12

9 -> 8 5 10 13

10 -> 9 6 11 14

11 -> 10 7 15

12 -> 8 13

13 -> 12 9 14

14 -> 13 10 15

15 -> 14 11

CROSSREFS

Cf. A223402.

Sequence in context: A192215 A347613 A280022 * A211735 A211746 A211755

Adjacent sequences:  A223393 A223394 A223395 * A223397 A223398 A223399

KEYWORD

nonn

AUTHOR

R. H. Hardin, Mar 19 2013

STATUS

approved

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Last modified January 21 14:37 EST 2022. Contains 350479 sequences. (Running on oeis4.)