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A251131 Number of (n+1) X (2+1) 0..2 arrays with no 2 X 2 subblock having the sum of its diagonal elements greater than the maximum of its antidiagonal elements. 1
133, 416, 1002, 2264, 4786, 9786, 19548, 38674, 76196, 150192, 296626, 587420, 1166206, 2320222, 4623712, 9225118, 18421072, 36804772, 73562342, 147065944, 294059610, 588031298, 1175956612, 2351786634, 4703423196, 9406669816 (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) = 6*a(n-1) - 13*a(n-2) + 10*a(n-3) + 5*a(n-4) - 14*a(n-5) + 9*a(n-6) - 2*a(n-7) for n>9.

Conjectures from Colin Barker, Nov 26 2018: (Start)

G.f.: x*(133 - 382*x + 235*x^2 + 330*x^3 - 597*x^4 + 264*x^5 + 27*x^6 - 26*x^7 - 4*x^8) / ((1 - x)^5*(1 + x)*(1 - 2*x)).

a(n) = (-873 + 49*(-1)^n + 841*2^(1+n) - 614*n - 11*n^2 + 38*n^3 + 5*n^4) / 12 for n>2.

(End)

EXAMPLE

Some solutions for n=4:

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

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

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

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

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

CROSSREFS

Column 2 of A251137.

Sequence in context: A259638 A070158 A055940 * A267288 A137879 A249108

Adjacent sequences:  A251128 A251129 A251130 * A251132 A251133 A251134

KEYWORD

nonn

AUTHOR

R. H. Hardin, Nov 30 2014

STATUS

approved

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Last modified May 21 18:53 EDT 2019. Contains 323444 sequences. (Running on oeis4.)