A240784 Number of 3 X n 0..1 arrays with no element equal to fewer vertical neighbors than horizontal neighbors, with new values 0..1 introduced in row major order.

4, 11, 20, 46, 97, 216, 472, 1043, 2296, 5066, 11169, 24636, 54332, 119835, 264300, 582934, 1285697, 2835696, 6254320, 13794339, 30424368, 67103058, 148000449, 326425268, 719953588, 1587907627, 3502240516, 7724434622, 17036776865

Offset

1,1

Links

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

Formula

Empirical: a(n) = 2*a(n-1) + a(n-2) - a(n-3) - a(n-5).

Empirical g.f.: x*(4 + 3*x - 6*x^2 - x^3 - 4*x^4) / ((1 - x)*(1 + x)*(1 - 2*x - x^3)). - Colin Barker, Oct 29 2018

Example

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

Crossrefs

Row 3 of A240783.

Sequence in context: A363604 A008262 A075099 * A345434 A297961 A240155

Adjacent sequences: A240781 A240782 A240783 * A240785 A240786 A240787

Keyword

nonn

Author

R. H. Hardin, Apr 12 2014

Status

approved