A250156 Number of length 2+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.

193, 3450, 26710, 129595, 468231, 1382188, 3522460, 8028405, 16761565, 32604286, 59831058, 104560495, 175295875, 283562160, 444647416, 678456553, 1010485305, 1472922370, 2105887630, 2958814371, 4091983423, 5578217140, 7504741140

Offset

1,1

Links

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

Formula

Empirical: a(n) = (11/7)*n^7 + 13*n^6 + (67/2)*n^5 + (97/2)*n^4 + (103/2)*n^3 + 34*n^2 + (139/14)*n + 1.

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

G.f.: x*(193 + 1906*x + 4514*x^2 + 1707*x^3 - 339*x^4 - 68*x^5 + 8*x^6 - x^7) / (1 - x)^8.

a(n) = 8*a(n-1) - 28*a(n-2) + 56*a(n-3) - 70*a(n-4) + 56*a(n-5) - 28*a(n-6) + 8*a(n-7) - a(n-8) for n>8.

(End)

Example

Some solutions for n=4:
..0....3....3....2....3....2....1....1....3....2....0....2....2....3....3....0
..1....1....2....4....3....0....2....3....3....1....2....2....1....2....0....3
..1....0....2....2....2....0....0....0....4....2....0....2....2....0....4....0
..1....2....2....3....2....4....3....3....1....1....1....2....3....2....4....2
..4....1....2....1....3....0....3....1....1....4....0....3....1....0....1....3
..3....2....4....2....0....0....0....0....1....1....4....2....0....0....1....0
..4....3....0....2....3....4....0....0....3....1....0....1....1....2....1....0
..0....3....4....3....4....2....4....4....2....0....0....2....1....3....3....0

Crossrefs

Row 2 of A250154.

Sequence in context: A166540 A178265 A201112 * A197112 A120851 A302332

Adjacent sequences: A250153 A250154 A250155 * A250157 A250158 A250159

Keyword

nonn

Author

R. H. Hardin, Nov 13 2014

Status

approved