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

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A225304 Number of nX3 -1,1 arrays such that the sum over i=1..n,j=1..3 of i*x(i,j) is zero and rows are nondecreasing (ways to put 3 thrusters pointing east or west at each of n positions 1..n distance from the hinge of a south-pointing gate without turning the gate) 1
0, 0, 6, 16, 0, 0, 474, 1576, 0, 0, 64700, 228876, 0, 0, 10659862, 38869960, 0, 0, 1941920508, 7211917300, 0, 0, 376790653888, 1416598649968, 0, 0, 76344225166632, 289560610889154, 0, 0, 15965033749025502, 60953934482465398, 0, 0 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,3

COMMENTS

Column 3 of A225310

LINKS

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

EXAMPLE

Some solutions for n=4

.-1.-1..1...-1.-1.-1....1..1..1...-1.-1.-1...-1.-1..1...-1.-1.-1...-1..1..1

.-1.-1.-1...-1..1..1...-1.-1.-1....1..1..1....1..1..1...-1.-1.-1...-1..1..1

.-1..1..1...-1.-1..1...-1.-1.-1....1..1..1...-1.-1.-1...-1.-1..1....1..1..1

.-1..1..1...-1..1..1....1..1..1...-1.-1.-1...-1..1..1....1..1..1...-1.-1.-1

CROSSREFS

Sequence in context: A191463 A068941 A235943 * A299709 A107777 A136140

Adjacent sequences:  A225301 A225302 A225303 * A225305 A225306 A225307

KEYWORD

nonn

AUTHOR

R. H. Hardin May 05 2013

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 October 19 04:40 EDT 2019. Contains 328211 sequences. (Running on oeis4.)