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A223557
Petersen graph (3,1) coloring a rectangular array: number of 2 X n 0..5 arrays where 0..5 label nodes of a graph with edges 0,1 0,3 3,5 3,4 1,2 1,4 4,5 2,0 2,5 and every array movement to a horizontal or antidiagonal neighbor moves along an edge of this graph, with the array starting at 0.
1
6, 27, 171, 1089, 6939, 44217, 281763, 1795473, 11441259, 72906921, 464583411, 2960456193, 18864859707, 120212193177, 766025913411, 4881332621169, 31105224694539, 198211242377097, 1263057797861523, 8048559615522273
OFFSET
1,1
COMMENTS
Row 2 of A223556.
LINKS
FORMULA
Empirical: a(n) = 7*a(n-1) - 4*a(n-2) for n>3.
Empirical g.f.: 3*x*(2 - x)*(1 - 2*x) / (1 - 7*x + 4*x^2). - Colin Barker, Aug 21 2018
EXAMPLE
Some solutions for n=3:
..0..1..0....0..3..4....0..1..0....0..1..0....0..1..0....0..2..1....0..3..0
..0..2..5....4..5..2....0..3..0....0..2..1....0..1..0....1..2..1....4..1..4
CROSSREFS
Cf. A223556.
Sequence in context: A144013 A318565 A092854 * A289022 A060977 A267630
KEYWORD
nonn
AUTHOR
R. H. Hardin, Mar 22 2013
STATUS
approved