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A251222 Number of (n+1) X (2+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. 1
49, 305, 1892, 11753, 72985, 453273, 2814985, 17482154, 108570830, 674266427, 4187452312, 26005680486, 161505221644, 1003009195172, 6229070707553, 38684911434209, 240248095245952, 1492032555580773, 9266092805568853 (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) - 8*a(n-3) - 8*a(n-4) + 3*a(n-5).

Empirical g.f.: x*(49 + 60*x - 74*x^2 - 60*x^3 + 24*x^4) / ((1 - x)*(1 + x)*(1 - 5*x - 8*x^2 + 3*x^3)). - Colin Barker, Nov 27 2018

EXAMPLE

Some solutions for n=4:

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

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

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

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

CROSSREFS

Column 2 of A251228.

Sequence in context: A017354 A239607 A227079 * A250967 A245033 A340124

Adjacent sequences: A251219 A251220 A251221 * A251223 A251224 A251225

KEYWORD

nonn

AUTHOR

R. H. Hardin, Nov 30 2014

STATUS

approved

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Last modified February 6 20:15 EST 2023. Contains 360111 sequences. (Running on oeis4.)