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A251221 Number of (n+1) X (1+1) 0..1 arrays with no 2 X 2 subblock having the minimum of its diagonal elements greater than the absolute difference of its antidiagonal elements. 3
14, 49, 171, 597, 2084, 7275, 25396, 88654, 309479, 1080349, 3771351, 13165272, 45958169, 160433700, 560052166, 1955065729, 6824867819, 23824682749, 83168718156, 290330652147, 1013504710004, 3538006716150, 12350698916311 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Column 1 of A251228.

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) - a(n-3).

Empirical g.f.: x*(14 + 7*x - 4*x^2) / (1 - 3*x - 2*x^2 + x^3). - Colin Barker, Feb 25 2018

EXAMPLE

Some solutions for n=4:

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

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

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

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

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

CROSSREFS

Cf. A251228.

Sequence in context: A043163 A043943 A084049 * A302467 A303249 A215569

Adjacent sequences:  A251218 A251219 A251220 * A251222 A251223 A251224

KEYWORD

nonn

AUTHOR

R. H. Hardin, Nov 30 2014

STATUS

approved

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Last modified August 22 03:53 EDT 2018. Contains 313964 sequences. (Running on oeis4.)