A251124 Number of (n+1) X (4+1) 0..1 arrays with no 2 X 2 subblock having the sum of its diagonal elements greater than the maximum of its antidiagonal elements.

72, 117, 173, 266, 401, 612, 938, 1452, 2266, 3565, 5646, 8991, 14379, 23071, 37107, 59788, 96455, 155750, 251656, 406798, 657784, 1063847, 1720828, 2783801, 4503681, 7286457, 11789033, 19074302, 30862061, 49935000, 80795606, 130729056

Offset

1,1

Links

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

Formula

Empirical: a(n) = 4*a(n-1) - 5*a(n-2) + a(n-3) + 2*a(n-4) - a(n-5) for n>6.

Empirical g.f.: x*(72 - 171*x + 65*x^2 + 87*x^3 - 59*x^4 + 3*x^5) / ((1 - x)^3*(1 - x - x^2)). - Colin Barker, Nov 26 2018

Example

Some solutions for n=4:
..0..0..0..1..0....0..0..0..0..0....0..0..1..0..0....0..0..0..0..1
..1..0..0..1..0....0..0..0..0..0....0..0..1..0..0....0..0..0..0..1
..1..0..0..1..0....0..0..0..0..0....0..0..1..0..0....0..0..0..0..1
..1..0..0..1..0....0..0..0..0..0....1..0..1..0..0....0..0..0..0..1
..1..0..0..1..0....1..1..1..0..0....1..0..1..0..0....1..0..0..0..1

Crossrefs

Column 4 of A251128.

Sequence in context: A143610 A166987 A339940 * A169644 A078667 A090784

Adjacent sequences: A251121 A251122 A251123 * A251125 A251126 A251127

Keyword

nonn

Author

R. H. Hardin, Nov 30 2014

Status

approved