login
The OEIS is supported by the many generous donors to the OEIS Foundation.

 

Logo
Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A200435 Number of -n..n arrays x(0..7) of 8 elements with zero sum and no two or three adjacent elements summing to zero. 1
0, 1928, 50592, 473034, 2591502, 10217182, 32233938, 86581308, 205946004, 445471164, 892792604, 1680711318, 3002811474, 5132333154, 8444609086, 13443374616, 20791260168, 31344775440, 46194094584, 66707951618, 94583955318 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

Row 5 of A200430.

LINKS

R. H. Hardin, Table of n, a(n) for n = 1..51

FORMULA

Empirical: a(n) = (19328/315)*n^7 - (18373/90)*n^6 + (18602/45)*n^5 - (20887/36)*n^4 + (46687/90)*n^3 - (48359/180)*n^2 + (12499/210)*n.

Conjectures from Colin Barker, May 21 2018: (Start)

G.f.: 2*x^2*(964 + 17584*x + 61141*x^2 + 57919*x^3 + 15963*x^4 + 1053*x^5) / (1 - x)^8.

a(n) = 8*a(n-1) - 28*a(n-2) + 56*a(n-3) - 70*a(n-4) + 56*a(n-5) - 28*a(n-6) + 8*a(n-7) - a(n-8) for n>8.

(End)

EXAMPLE

Some solutions for n=3:

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

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

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

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

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

.-2...-3....2....1....3...-1....1...-3...-2....1...-2...-2...-1...-1....2...-1

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

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

CROSSREFS

Cf. A200430.

Sequence in context: A258841 A099482 A253337 * A252108 A220717 A162386

Adjacent sequences:  A200432 A200433 A200434 * A200436 A200437 A200438

KEYWORD

nonn

AUTHOR

R. H. Hardin, Nov 17 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 | Recents
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified May 25 19:19 EDT 2022. Contains 354071 sequences. (Running on oeis4.)