A253351 Number of (2+1) X (n+1) 0..1 arrays with every 2 X 2 subblock diagonal maximum minus antidiagonal maximum nondecreasing horizontally, vertically and ne-to-sw antidiagonally.

47, 173, 724, 3160, 13810, 60368, 263920, 1153880, 5044984, 22057880, 96442840, 421674392, 1843677400, 8061072920, 35245271896, 154102230680, 673778278360, 2945948129048, 12880513877080, 56317230045080, 246234772676824

Offset

1,1

Links

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

Formula

Empirical: a(n) = 5*a(n-1) - 12*a(n-3) for n>6.

Empirical g.f.: x*(47 - 62*x - 141*x^2 + 104*x^3 + 86*x^4 + 6*x^5) / ((1 - 2*x)*(1 - 3*x - 6*x^2)). - Colin Barker, Dec 11 2018

Example

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

Crossrefs

Row 2 of A253350.

Sequence in context: A216827 A139992 A142916 * A253344 A227282 A204610

Adjacent sequences: A253348 A253349 A253350 * A253352 A253353 A253354

Keyword

nonn

Author

R. H. Hardin, Dec 30 2014

Status

approved