login
The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A267228 Number of length-n 0..4 arrays with no following elements greater than or equal to the first repeated value. 1
5, 25, 110, 470, 1980, 8274, 34396, 142474, 588596, 2426738, 9989292, 41065818, 168636772, 691859842, 2836150748, 11617837802, 47559474708, 194575978386, 795613053964, 3251559375226, 13282278193604, 54232112235170 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Column 4 of A267232.

LINKS

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

FORMULA

Empirical: a(n) = 14*a(n-1) -75*a(n-2) +190*a(n-3) -224*a(n-4) +96*a(n-5) for n>6.

Conjectures from Colin Barker, Feb 05 2018: (Start)

G.f.: x*(5 - 45*x + 135*x^2 - 145*x^3 + 20*x^4 + 24*x^5) / ((1 - x)*(1 - 2*x)*(1 - 3*x)*(1 - 4*x)^2).

a(n) = (2*(-3*2^(1+n) - 8*3^n + 41*4^n - 8) + 3*4^n*n) / 48 for n>1.

(End)

EXAMPLE

Some solutions for n=6:

..1....0....0....4....0....4....1....2....2....0....1....1....2....3....1....3

..4....4....3....2....1....4....2....3....0....2....3....4....0....1....3....1

..3....2....2....3....0....0....0....2....1....2....2....1....3....4....0....2

..0....4....3....1....4....3....1....0....2....1....1....3....4....0....2....3

..4....0....2....0....2....3....4....4....4....0....3....1....2....3....0....0

..2....2....2....0....1....0....0....3....1....0....1....3....3....3....3....4

CROSSREFS

Cf. A267232.

Sequence in context: A282077 A282085 A290920 * A183926 A092440 A196985

Adjacent sequences:  A267225 A267226 A267227 * A267229 A267230 A267231

KEYWORD

nonn

AUTHOR

R. H. Hardin, Jan 12 2016

STATUS

approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified June 18 04:41 EDT 2021. Contains 345098 sequences. (Running on oeis4.)