A249701 Number of length n+3 0..2 arrays with every four consecutive terms having the maximum of some two terms equal to the minimum of the remaining two terms.

39, 69, 125, 221, 377, 659, 1177, 2119, 3805, 6857, 12437, 22681, 41475, 76011, 139645, 257161, 474439, 876539, 1621387, 3002407, 5564769, 10321599, 19156321, 35571383, 66081147, 122803551, 228283091, 424467169, 789412673, 1468380739

Offset

1,1

Links

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

Formula

Empirical: a(n) = 3*a(n-1) - 3*a(n-2) + 2*a(n-3) + 2*a(n-4) - 5*a(n-5) + a(n-6) -a(n-7) - 2*a(n-8) + 2*a(n-10).

Empirical g.f.: x*(39 - 48*x + 35*x^2 - 25*x^3 - 127*x^4 - 2*x^5 - 55*x^6 - 36*x^7 + 34*x^8 + 54*x^9) / ((1 + x)*(1 - 2*x + 2*x^2 - 2*x^3)*(1 - 2*x + x^2 - x^3 - x^4 + x^6)). - Colin Barker, Nov 09 2018

Example

Some solutions for n=6:
..0....0....1....2....1....2....1....2....1....1....2....0....1....1....1....1
..1....1....0....0....2....2....2....1....0....1....1....1....0....0....1....2
..2....0....1....1....1....2....0....1....2....1....1....2....1....1....1....1
..1....0....1....1....0....2....1....1....1....1....1....1....1....2....1....1
..0....0....1....2....1....0....1....1....1....0....2....0....1....1....1....0
..1....0....1....1....1....2....1....1....1....1....0....1....0....1....1....1
..1....0....1....1....1....2....1....2....1....1....1....1....1....1....1....1
..2....0....1....0....1....2....2....0....0....1....1....2....1....1....0....1
..0....1....0....1....0....2....1....1....2....1....2....1....2....0....1....0

Crossrefs

Column 2 of A249707.

Sequence in context: A165461 A020166 A046448 * A039467 A250657 A243577

Adjacent sequences: A249698 A249699 A249700 * A249702 A249703 A249704

Keyword

nonn

Author

R. H. Hardin, Nov 04 2014

Status

approved