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A197564 Number of n X n X n 0..6 triangular arrays with each element equal to the number its zero neighbors. 1
1, 3, 4, 18, 51, 266, 1518, 11396, 111218, 1345019, 21178437, 420441727, 10691248879, 346431341394, 14306876354446, 754052504644414 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,2
COMMENTS
Also the number of maximal independent vertex sets (and minimal vertex covers) in the (n-1)-triangular grid graph. - Eric W. Weisstein, Jun 14 and Aug 07 2017
LINKS
Eric Weisstein's World of Mathematics, Minimal Vertex Cover
Eric Weisstein's World of Mathematics, Maximal Independent Vertex Set
Eric Weisstein's World of Mathematics, Triangular Grid Graph
EXAMPLE
Some solutions for 5 X 5 X 5:
......1..........0..........0..........0..........0..........1..........0
.....1.0........2.2........1.2........2.1........1.2........0.2........2.2
....1.2.2......0.2.0......1.1.0......0.1.1......1.1.0......1.2.0......1.0.1
...0.2.0.2....2.2.2.2....0.2.2.2....2.2.1.0....0.1.2.2....1.1.1.2....1.2.2.1
..1.1.1.2.0..0.2.0.2.0..1.2.0.2.0..1.0.1.1.1..1.1.1.0.1..1.0.1.1.0..0.2.0.2.0
CROSSREFS
Sequence in context: A025113 A290956 A089427 * A222691 A254201 A222795
KEYWORD
nonn
AUTHOR
R. H. Hardin, Oct 16 2011
STATUS
approved

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Last modified April 24 04:14 EDT 2024. Contains 371918 sequences. (Running on oeis4.)