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A242234
Number of length n+3+1 0..3 arrays with every value 0..3 appearing at least once in every consecutive 3+2 elements, and new values 0..3 introduced in order.
2
10, 22, 43, 82, 157, 304, 586, 1129, 2176, 4195, 8086, 15586, 30043, 57910, 111625, 215164, 414742, 799441, 1540972, 2970319, 5725474, 11036206, 21272971, 41004970, 79039621, 152353768, 293671330, 566069689, 1091134408, 2103229195, 4054104622
OFFSET
1,1
COMMENTS
Column 3 of A242239.
LINKS
FORMULA
Empirical: a(n) = a(n-1) +a(n-2) +a(n-3) +a(n-4).
Conjecture: a(n) = 9*A145112(n-1) + A016777(n-1). - R. J. Mathar, Aug 16 2017
Empirical g.f.: x*(10 + 12*x + 11*x^2 + 7*x^3) / (1 - x - x^2 - x^3 - x^4). - Colin Barker, Mar 19 2018
EXAMPLE
Some solutions for n=5:
..0....0....0....0....0....0....0....0....0....0....0....0....0....0....0....0
..1....1....1....1....1....0....1....1....1....1....0....1....1....1....1....1
..1....2....2....2....2....1....2....0....1....0....1....2....2....2....2....0
..2....1....3....3....0....2....3....2....2....2....2....0....0....3....1....2
..3....3....0....0....3....3....0....3....3....3....3....3....3....0....3....3
..0....0....1....3....1....0....2....0....0....0....0....1....2....1....0....1
..2....2....2....1....2....0....1....1....1....1....1....2....1....2....2....3
..1....1....3....2....2....1....2....1....2....2....1....0....0....3....0....0
..1....3....0....2....0....2....3....2....1....3....2....2....0....3....1....2
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin, May 08 2014
STATUS
approved