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!)
A253230 Number of (n+1) X (7+1) 0..1 arrays with every 2 X 2 subblock diagonal minimum minus antidiagonal minimum nondecreasing horizontally and diagonal maximum minus antidiagonal maximum nondecreasing vertically. 1
6740, 9551, 6231, 8216, 11022, 15363, 22656, 35736, 60273, 107607, 200418, 384066, 749271, 1477473, 2931552, 5837268, 11646141, 23261211, 46488558, 92940342, 185840883, 371638821, 743231436, 1486413288, 2972773497, 5945490303 (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) = 5*a(n-1) - 9*a(n-2) + 7*a(n-3) - 2*a(n-4) for n>8.

Conjectures from Colin Barker, Dec 11 2018: (Start)

G.f.: x*(6740 - 24149*x + 19136*x^2 + 15840*x^3 - 27356*x^4 + 9682*x^5 - 11*x^6 + x^7) / ((1 - x)^3*(1 - 2*x)).

a(n) = (3/32)*(25728 + 945*2^n + 9200*n + 624*n^2) for n>4.

(End)

EXAMPLE

Some solutions for n=4:

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

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

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

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

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

CROSSREFS

Column 7 of A253231.

Sequence in context: A257486 A345591 A345849 * A253349 A253356 A204615

Adjacent sequences:  A253227 A253228 A253229 * A253231 A253232 A253233

KEYWORD

nonn

AUTHOR

R. H. Hardin, Dec 29 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 | Recents
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified August 13 05:18 EDT 2022. Contains 356077 sequences. (Running on oeis4.)