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

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A253436 Number of (2+1) X (n+1) 0..1 arrays with every 2 X 2 subblock diagonal minus antidiagonal sum nondecreasing horizontally, vertically and ne-to-sw antidiagonally. 1
39, 58, 70, 102, 174, 318, 606, 1182, 2334, 4638, 9246, 18462, 36894, 73758, 147486, 294942, 589854, 1179678, 2359326, 4718622, 9437214, 18874398, 37748766, 75497502, 150994974, 301989918, 603979806, 1207959582, 2415919134, 4831838238 (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) = 3*a(n-1) - 2*a(n-2) for n>5.

Empirical: a(n) = 9*2^(n-1) + 30 for n>3.

Empirical g.f.: x*(39 - 59*x - 26*x^2 + 8*x^3 + 8*x^4) / ((1 - x)*(1 - 2*x)). - Colin Barker, Dec 12 2018

EXAMPLE

Some solutions for n=4:

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

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

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

CROSSREFS

Row 2 of A253435.

Sequence in context: A156333 A116281 A168530 * A253429 A050780 A039353

Adjacent sequences:  A253433 A253434 A253435 * A253437 A253438 A253439

KEYWORD

nonn

AUTHOR

R. H. Hardin, Dec 31 2014

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 November 21 22:40 EST 2019. Contains 329383 sequences. (Running on oeis4.)