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A221461
Number of 0..6 arrays of length n with each element unequal to at least one neighbor, starting with 0
2
0, 6, 36, 252, 1728, 11880, 81648, 561168, 3856896, 26508384, 182191680, 1252200384, 8606352384, 59151316608, 406546013952, 2794183983360, 19204379983872, 131991383803392, 907174582723584, 6234995799161856
OFFSET
1,2
COMMENTS
Column 6 of A221463
LINKS
FORMULA
Empirical: a(n) = 6*a(n-1) +6*a(n-2)
EXAMPLE
Some solutions for n=6
..0....0....0....0....0....0....0....0....0....0....0....0....0....0....0....0
..6....4....2....3....2....4....2....6....3....3....1....2....1....5....5....3
..3....2....5....0....2....5....1....6....2....1....2....4....4....5....0....3
..4....4....4....3....6....3....2....2....0....4....2....0....0....4....0....0
..4....3....6....6....1....5....2....2....5....6....3....4....3....0....5....3
..6....4....4....2....6....0....3....4....3....2....6....2....6....4....1....4
CROSSREFS
Sequence in context: A367260 A366496 A366500 * A374986 A090015 A299330
KEYWORD
nonn
AUTHOR
R. H. Hardin Jan 17 2013
STATUS
approved