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!)
A224404 Number of n X 3 0..1 arrays with rows unimodal and antidiagonals nondecreasing. 1
7, 28, 100, 358, 1288, 4636, 16684, 60040, 216064, 777544, 2798128, 10069552, 36237040, 130405312, 469286272, 1688808544, 6077472256, 21870844480, 78706050496, 283237457536, 1019279418112, 3668054858368, 13200135512320 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Column 3 of A224409.

LINKS

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

FORMULA

Empirical: a(n) = 4*a(n-1) - 2*a(n-2) + 2*a(n-3).

Empirical g.f.: x*(7 + 2*x^2) / (1 - 4*x + 2*x^2 - 2*x^3). - Colin Barker, Aug 30 2018

EXAMPLE

Some solutions for n=3:

..0..1..0....0..0..0....1..1..0....1..1..0....0..0..0....0..1..0....0..0..1

..1..1..0....0..0..0....1..1..1....1..0..0....0..1..0....1..0..0....1..1..0

..1..0..0....0..0..1....1..1..0....0..0..0....1..1..1....0..1..1....1..1..0

CROSSREFS

Cf. A224409.

Sequence in context: A356038 A241400 A219411 * A331197 A024207 A000416

Adjacent sequences:  A224401 A224402 A224403 * A224405 A224406 A224407

KEYWORD

nonn

AUTHOR

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

License Agreements, Terms of Use, Privacy Policy. .

Last modified August 8 14:39 EDT 2022. Contains 356009 sequences. (Running on oeis4.)