A267467 Number of length-n 0..4 arrays with no following elements larger than the first repeated value.

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

R. H. Hardin, Table of n, a(n) for n = 1..210

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

Adjacent sequences: A267464 A267465 A267466 * A267468 A267469 A267470

Keyword

nonn

Author

R. H. Hardin, Jan 15 2016

Status

approved