login
A250084
Number of length 3+5 0..n arrays with every six consecutive terms having the maximum of some two terms equal to the minimum of the remaining four terms.
1
144, 2228, 15472, 68863, 232096, 647122, 1572320, 3441309, 6938416, 13092816, 23393360, 39926107, 65536576, 104018734, 160332736, 240853433, 353651664, 508810348, 718777392, 998757431, 1367144416, 1845997066, 2461559200
OFFSET
1,1
LINKS
FORMULA
Empirical: a(n) = (2/5)*n^7 + (19/3)*n^6 + (47/2)*n^5 + 37*n^4 + (183/5)*n^3 + (83/3)*n^2 + (23/2)*n + 1.
Conjectures from Colin Barker, Nov 11 2018: (Start)
G.f.: x*(144 + 1076*x + 1680*x^2 - 593*x^3 - 280*x^4 - 18*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....2....4....2....2....2....3....3....4....3....2....4....3....1....3....0
..2....4....2....4....0....3....2....2....0....3....3....1....1....1....1....1
..0....4....1....0....0....0....4....0....0....3....2....4....1....1....1....0
..3....0....4....0....1....1....4....2....1....0....2....2....2....1....4....1
..0....0....1....0....0....1....0....4....0....4....1....2....3....1....4....0
..0....0....1....3....4....2....2....2....4....3....4....2....0....3....0....4
..0....0....3....0....1....2....3....4....3....3....3....2....1....3....1....0
..3....4....1....2....0....2....2....2....0....4....4....2....4....0....2....0
CROSSREFS
Row 3 of A250081.
Sequence in context: A368508 A066445 A008431 * A280025 A223687 A268625
KEYWORD
nonn
AUTHOR
R. H. Hardin, Nov 11 2014
STATUS
approved