login
This site is supported by donations to The OEIS Foundation.

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A200877 Number of 0..n arrays x(0..8) of 9 elements without any interior element greater than both neighbors or less than both neighbors. 1
110, 1523, 9858, 42479, 141688, 395929, 971416, 2156867, 4424298, 8509105, 15512938, 27033149, 45322876, 73486107, 115712352, 177555837, 266264422, 391163735, 564102306, 799963779, 1117252576, 1538759685, 2092315544 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Row 7 of A200871.

LINKS

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

FORMULA

Empirical: a(n) = (1/181440)*n^9 + (131/20160)*n^8 + (8893/30240)*n^7 + (4621/1440)*n^6 + (118933/8640)*n^5 + (83957/2880)*n^4 + (763489/22680)*n^3 + (36343/1680)*n^2 + (9169/1260)*n + 1.

Conjectures from Colin Barker, Oct 16 2017: (Start)

G.f.: x*(110 + 423*x - 422*x^2 - 766*x^3 + 848*x^4 - 246*x^5 + 90*x^6 - 44*x^7 + 10*x^8 - x^9) / (1 - x)^10.

a(n) = 10*a(n-1) - 45*a(n-2) + 120*a(n-3) - 210*a(n-4) + 252*a(n-5) - 210*a(n-6) + 120*a(n-7) - 45*a(n-8) + 10*a(n-9) - a(n-10) for n>10.

(End)

EXAMPLE

Some solutions for n=3

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

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

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

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

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

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

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

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

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

CROSSREFS

Sequence in context: A248468 A231967 A232339 * A205348 A008450 A163729

Adjacent sequences:  A200874 A200875 A200876 * A200878 A200879 A200880

KEYWORD

nonn

AUTHOR

R. H. Hardin, Nov 23 2011

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 March 19 00:15 EDT 2019. Contains 321306 sequences. (Running on oeis4.)