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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
OFFSET
1,1
LINKS
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 A334037 A137879
KEYWORD
nonn
AUTHOR
R. H. Hardin, Nov 30 2014
STATUS
approved