A251048 - OEIS

A251048

Number of (n+1) X (1+1) 0..3 arrays with no 2 X 2 subblock having the sum of its diagonal elements greater than the absolute difference of its antidiagonal elements.

66, 290, 854, 2243, 5449, 12858, 29759, 68506, 157205, 360885, 828728, 1904810, 4380530, 10079260, 23198280, 53404661, 122956951, 283114508, 651911889, 1501161236, 3456777827, 7960112783, 18330262426, 42210375756, 97200890000

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OFFSET

1,1

LINKS

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

FORMULA

Empirical: a(n) = 7*a(n-1) - 18*a(n-2) + 17*a(n-3) + 10*a(n-4) - 39*a(n-5) + 38*a(n-6) - 17*a(n-7) + 3*a(n-8) for n>9.

Empirical g.f.: x*(66 - 172*x + 12*x^2 + 363*x^3 - 470*x^4 + 245*x^5 - 34*x^6 - 18*x^7 + 6*x^8) / ((1 - x)^6*(1 - x - 3*x^2)). - Colin Barker, Nov 24 2018

EXAMPLE

Some solutions for n=4:

..0..2....2..3....0..3....3..3....2..2....0..3....0..3....0..2....0..3....0..3

..0..2....0..0....0..3....0..0....0..0....0..0....0..0....0..0....1..2....0..3

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

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

..2..1....0..0....0..1....3..0....1..0....1..0....0..0....3..1....2..0....3..1

CROSSREFS

Column 1 of A251055.

Sequence in context: A242726 A271739 A251055 * A259292 A258958 A120102

Adjacent sequences: A251045 A251046 A251047 * A251049 A251050 A251051

KEYWORD

nonn

AUTHOR

R. H. Hardin, Nov 29 2014

STATUS

approved