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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 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

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

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: A186934 A066445 A008431 * A280025 A223687 A268625

Adjacent sequences:  A250081 A250082 A250083 * A250085 A250086 A250087

KEYWORD

nonn

AUTHOR

R. H. Hardin, Nov 11 2014

STATUS

approved

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Last modified December 16 01:43 EST 2019. Contains 330013 sequences. (Running on oeis4.)