A200528 Number of n X 2 0..2 arrays with every row and column running average nondecreasing rightwards and downwards.

6, 20, 57, 146, 354, 825, 1873, 4169, 9144, 19825, 42590, 90815, 192457, 405760, 851740, 1781227, 3713015, 7718092, 16003641, 33111477, 68374642, 140947848, 290098848, 596244613, 1223916576, 2509450811, 5139839214, 10517282966

Offset

1,1

Comments

Column 2 of A200534.

Links

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

Formula

Empirical: a(n) = 7*a(n-1) -16*a(n-2) +6*a(n-3) +27*a(n-4) -33*a(n-5) -3*a(n-6) +24*a(n-7) -11*a(n-8) -4*a(n-9) +4*a(n-10).

Empirical g.f.: x*(6 - 22*x + 13*x^2 + 31*x^3 - 38*x^4 - x^5 + 25*x^6 - 11*x^7 - 4*x^8 + 4*x^9) / ((1 - x)*(1 + x)*(1 - 2*x)^2*(1 - x - x^2)*(1 - 2*x + x^3 - x^4)). - Colin Barker, May 21 2018

Example

Some solutions for n=4:
..0..0....0..1....1..2....0..0....0..0....0..0....0..0....0..0....0..1....0..0
..1..1....2..2....1..2....0..2....1..1....0..2....0..1....1..1....1..2....0..1
..1..2....1..2....1..2....0..1....2..2....0..1....2..2....2..2....1..2....0..2
..1..1....1..2....2..2....1..1....1..1....0..1....1..1....1..2....2..2....0..2

Crossrefs

Cf. A200534.

Sequence in context: A048778 A048611 A292480 * A127982 A109164 A212689

Adjacent sequences: A200525 A200526 A200527 * A200529 A200530 A200531

Keyword

nonn

Author

R. H. Hardin, Nov 18 2011

Status

approved