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!)
A251276 Number of (n+1) X (1+1) 0..3 arrays with no 2 X 2 subblock having its maximum diagonal element less than its minimum antidiagonal element. 1
230, 3264, 46244, 655040, 9278296, 131421696, 1861511440, 26367218944, 373476205664, 5290071598080, 74930764222016, 1061350366002176, 15033405986262400, 212939386264141824, 3016161624583446784 (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) = 16*a(n-1) - 26*a(n-2).

Conjectures from Colin Barker, Nov 27 2018: (Start)

G.f.: 2*x*(115 - 208*x) / (1 - 16*x + 26*x^2).

a(n) = ((8-sqrt(38))^n*(-51+8*sqrt(38)) + (8+sqrt(38))^n*(51+8*sqrt(38))) / sqrt(38).

(End)

EXAMPLE

Some solutions for n=3:

..0..0....3..2....2..0....3..2....0..2....1..0....1..3....2..3....3..3....0..0

..3..0....2..0....2..1....2..2....1..1....3..2....1..0....0..0....1..3....1..0

..0..0....3..0....3..0....2..0....1..2....1..1....2..3....2..3....1..3....2..0

..1..2....2..2....1..3....3..2....2..2....1..2....1..0....0..0....2..2....2..1

CROSSREFS

Column 1 of A251283.

Sequence in context: A211716 A251445 A251283 * A194490 A232379 A333136

Adjacent sequences:  A251273 A251274 A251275 * A251277 A251278 A251279

KEYWORD

nonn

AUTHOR

R. H. Hardin, Dec 01 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 April 22 14:20 EDT 2021. Contains 343177 sequences. (Running on oeis4.)