login
The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A229447 Number of 4 X n 0..2 arrays with horizontal differences mod 3 never 1, vertical differences mod 3 never -1, and rows and columns lexicographically nondecreasing. 1
12, 25, 53, 109, 212, 387, 665, 1083, 1684, 2517, 3637, 5105, 6988, 9359, 12297, 15887, 20220, 25393, 31509, 38677, 47012, 56635, 67673, 80259, 94532, 110637, 128725, 148953, 171484, 196487, 224137, 254615, 288108, 324809, 364917, 408637, 456180 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

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

FORMULA

Empirical: a(n) = (1/4)*n^4 - (1/3)*n^3 + (13/4)*n^2 + (11/6)*n + 7.

Conjectures from Colin Barker, Sep 17 2018: (Start)

G.f.: x*(12 - 35*x + 48*x^2 - 26*x^3 + 7*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=4:

..0..0..0..2....0..0..0..2....0..0..0..2....0..2..2..2....0..0..0..0

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

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

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

CROSSREFS

Row 4 of A229445.

Sequence in context: A195143 A280321 A198274 * A175523 A280391 A058848

Adjacent sequences:  A229444 A229445 A229446 * A229448 A229449 A229450

KEYWORD

nonn

AUTHOR

R. H. Hardin, Sep 23 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 June 12 14:20 EDT 2021. Contains 344956 sequences. (Running on oeis4.)