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A267467
Number of length-n 0..4 arrays with no following elements larger than the first repeated value.
1
5, 25, 115, 515, 2285, 10119, 44901, 200119, 897301, 4052183, 18444197, 84651063, 391805877, 1828676887, 8604122053, 40793238647, 194778656213, 936040595031, 4524410973669, 21981448319671, 107275320299509, 525571712299415
OFFSET
1,1
COMMENTS
Column 4 of A267471.
LINKS
FORMULA
Empirical: a(n) = 19*a(n-1) -145*a(n-2) +565*a(n-3) -1174*a(n-4) +1216*a(n-5) -480*a(n-6).
Conjectures from Colin Barker, Feb 05 2018: (Start)
G.f.: x*(5 - 70*x + 365*x^2 - 870*x^3 + 920*x^4 - 326*x^5) / ((1 - x)*(1 - 2*x)*(1 - 3*x)*(1 - 4*x)^2*(1 - 5*x)).
a(n) = (-80 - 15*2^(2+n) - 80*3^n + 335*4^n + 48*5^n) / 240 + 4^(-2+n)*n.
(End)
EXAMPLE
Some solutions for n=7:
..1....3....1....4....1....2....4....4....3....1....2....1....1....3....4....3
..4....4....4....1....3....1....4....0....3....0....3....4....2....1....1....1
..4....3....0....3....1....3....0....3....1....2....1....2....3....0....3....4
..1....4....1....3....3....0....0....1....2....4....3....1....1....4....3....3
..4....2....3....1....4....1....2....4....1....2....4....2....0....4....0....1
..1....1....2....2....4....2....2....2....2....3....1....0....4....4....0....0
..0....2....4....2....3....0....3....0....0....0....3....1....2....3....1....4
CROSSREFS
Cf. A267471.
Sequence in context: A369769 A261383 A089947 * A123890 A123894 A200781
KEYWORD
nonn
AUTHOR
R. H. Hardin, Jan 15 2016
STATUS
approved