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!)
A201814 Number of arrays of 6 integers in -n..n with sum zero and equal numbers of elements greater than zero and less than zero. 1
141, 1001, 4621, 15681, 42821, 99961, 207621, 394241, 697501, 1165641, 1858781, 2850241, 4227861, 6095321, 8573461, 11801601, 15938861, 21165481, 27684141, 35721281, 45528421, 57383481, 71592101, 88488961, 108439101, 131839241 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Row 6 of A201811.

LINKS

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

FORMULA

Empirical: a(n) = 11*n^5 + 65*n^3 + 64*n + 1.

Conjectures from Colin Barker, May 25 2018: (Start)

G.f.: x*(141 + 155*x + 730*x^2 + 150*x^3 + 145*x^4 - x^5) / (1 - x)^6.

a(n) = 6*a(n-1) - 15*a(n-2) + 20*a(n-3) - 15*a(n-4) + 6*a(n-5) - a(n-6) for n>6.

(End)

EXAMPLE

Some solutions for n=6:

..6....4....2...-5...-6....6....2...-2...-4...-4...-4....0....4...-4....5...-4

.-5....1....6...-1....2....5...-4...-4...-1....1...-3....5...-1....1...-3...-1

.-4...-4...-5....3....5....1...-2....0....3...-1....4...-4....3...-4...-5....4

..1...-2...-4....5...-1...-5....2....2...-6....6....1....0...-4...-1....5....1

.-1....4...-3...-4...-6...-5...-1....0....6....1...-3...-2...-6....2....2...-4

..3...-3....4....2....6...-2....3....4....2...-3....5....1....4....6...-4....4

CROSSREFS

Cf. A201811.

Sequence in context: A068046 A186954 A235760 * A235543 A204469 A201553

Adjacent sequences:  A201811 A201812 A201813 * A201815 A201816 A201817

KEYWORD

nonn

AUTHOR

R. H. Hardin, Dec 05 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 January 22 15:54 EST 2022. Contains 350481 sequences. (Running on oeis4.)