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

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A224000 Number of 2 X n 0..2 arrays with antidiagonals unimodal and rows and diagonals nondecreasing. 1
9, 31, 76, 155, 281, 469, 736, 1101, 1585, 2211, 3004, 3991, 5201, 6665, 8416, 10489, 12921, 15751, 19020, 22771, 27049, 31901, 37376, 43525, 50401, 58059, 66556, 75951, 86305, 97681, 110144, 123761, 138601, 154735, 172236, 191179, 211641, 233701 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Row 2 of A223999.

LINKS

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

FORMULA

Empirical: a(n) = (1/12)*n^4 + 1*n^3 + (41/12)*n^2 + (7/2)*n + 1.

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

G.f.: x*(9 - 14*x + 11*x^2 - 5*x^3 + x^4) / (1 - x)^5.

a(n) = 5*a(n-1) - 10*a(n-2) + 10*a(n-3) - 5*a(n-4) + a(n-5) for n>5.

(End)

EXAMPLE

Some solutions for n=3:

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

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

CROSSREFS

Cf. A223999.

Sequence in context: A168297 A004126 A177342 * A118444 A321598 A048374

Adjacent sequences:  A223997 A223998 A223999 * A224001 A224002 A224003

KEYWORD

nonn

AUTHOR

R. H. Hardin, Mar 30 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 September 20 12:13 EDT 2019. Contains 327231 sequences. (Running on oeis4.)