A250157 Number of length 3+6 0..n arrays with every seven consecutive terms having the maximum of some two terms equal to the minimum of the remaining five terms.

354, 8377, 79740, 455055, 1879526, 6219899, 17519352, 43657365, 98808010, 206916501, 406440244, 756627027, 1345629390, 2300780615, 3801384176, 6094394889, 9513396402, 14501306065, 21637264620, 31668194551, 45545537334

Offset

1,1

Links

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

Formula

Empirical: a(n) = (55/84)*n^8 + (67/7)*n^7 + (151/4)*n^6 + 70*n^5 + (1061/12)*n^4 + (521/6)*n^3 + (1377/28)*n^2 + (445/42)*n + 1.

Conjectures from Colin Barker, Nov 12 2018: (Start)

G.f.: x*(354 + 5191*x + 17091*x^2 + 9231*x^3 - 4393*x^4 - 1117*x^5 + 51*x^6 - 9*x^7 + x^8) / (1 - x)^9.

a(n) = 9*a(n-1) - 36*a(n-2) + 84*a(n-3) - 126*a(n-4) + 126*a(n-5) - 84*a(n-6) + 36*a(n-7) - 9*a(n-8) + a(n-9) for n>9.

(End)

Example

Some solutions for n=3:
..0....3....0....1....2....1....1....3....2....0....1....0....2....3....1....3
..1....0....3....3....1....0....1....1....0....3....2....2....2....1....1....3
..0....1....3....0....0....3....1....0....3....3....1....0....0....3....1....1
..2....3....2....3....0....1....3....1....1....3....3....0....0....3....0....1
..0....3....2....1....0....0....2....1....1....0....0....3....2....0....2....1
..0....1....2....0....1....2....2....3....2....1....3....3....0....0....3....3
..3....1....3....0....0....0....1....3....1....0....1....0....1....0....2....3
..0....3....3....0....1....0....1....1....2....0....2....2....1....2....1....1
..2....1....0....0....0....1....2....2....1....1....1....2....2....1....3....3

Crossrefs

Row 3 of A250154.

Sequence in context: A176197 A157668 A374696 * A293563 A241960 A221450

Adjacent sequences: A250154 A250155 A250156 * A250158 A250159 A250160

Keyword

nonn

Author

R. H. Hardin, Nov 13 2014

Status

approved