A235653 - OEIS

A235653

Number of (n+1) X (1+1) 0..1 arrays with the difference of the upper median and minimum value of each 2 X 2 subblock in lexicographically nondecreasing order rowwise and columnwise.

16, 52, 160, 476, 1392, 4020, 11520, 32828, 93200, 263892, 745824, 2105116, 5936304, 16729076, 47122368, 132690428, 373551952, 1051454740, 2959233056, 8327823580, 23434631152, 65942655540, 185550334592, 522092927932, 1469018657424

(list; graph; refs; listen; history; text; internal format)

OFFSET

1,1

COMMENTS

Column 1 of A235660.

LINKS

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

FORMULA

Empirical: a(n) = 4*a(n-1) - a(n-2) - 8*a(n-3) + 4*a(n-4).

Empirical g.f.: 4*x*(4 - 3*x - 8*x^2 + 4*x^3) / ((1 - 2*x)*(1 - 2*x - 3*x^2 + 2*x^3)). - Colin Barker, Mar 19 2018

EXAMPLE

Some solutions for n=5:

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

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

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

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

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

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

CROSSREFS

Cf. A235660.

Sequence in context: A217736 A211578 A211592 * A354886 A087701 A211586

Adjacent sequences: A235650 A235651 A235652 * A235654 A235655 A235656

KEYWORD

nonn

AUTHOR

R. H. Hardin, Jan 13 2014

STATUS

approved