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A249713 Number of length 7+3 0..n arrays with every four consecutive terms having the maximum of some two terms equal to the minimum of the remaining two terms. 1
72, 1177, 7056, 27113, 80360, 200489, 442144, 888465, 1659976, 2924889, 4910896, 7918521, 12336104, 18656489, 27495488, 39612193, 55931208, 77566873, 105849552, 142354057, 188930280, 247736105, 321272672, 412422065, 524487496, 661236057 (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) = (1/70)*n^7 + (19/15)*n^6 + (178/15)*n^5 + 30*n^4 + (851/30)*n^3 + (56/15)*n^2 - (446/105)*n + 1.

Conjectures from Colin Barker, Nov 10 2018: (Start)

G.f.: x*(72 + 601*x - 344*x^2 - 411*x^3 + 152*x^4 - 5*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=5:

..5....4....1....3....1....3....5....1....1....4....3....5....2....2....3....3

..0....0....2....3....5....1....0....3....3....4....3....0....2....4....1....0

..1....4....1....3....1....0....3....1....1....4....3....4....4....4....2....1

..1....5....1....3....1....1....3....1....1....4....3....4....2....4....2....1

..1....4....0....3....0....2....3....1....1....4....0....4....2....2....3....2

..1....3....3....3....1....1....4....1....0....1....4....0....2....4....2....1

..0....4....1....3....4....1....1....0....1....4....3....4....2....4....2....1

..1....5....1....3....1....0....3....4....3....4....3....4....2....5....2....1

..3....4....1....4....0....3....3....1....1....5....1....5....1....4....2....5

..1....2....4....3....1....1....4....1....0....2....3....3....4....0....4....0

CROSSREFS

Row 7 of A249707.

Sequence in context: A064567 A269088 A168194 * A269074 A200556 A239423

Adjacent sequences:  A249710 A249711 A249712 * A249714 A249715 A249716

KEYWORD

nonn

AUTHOR

R. H. Hardin, Nov 04 2014

STATUS

approved

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Last modified April 5 16:53 EDT 2020. Contains 333245 sequences. (Running on oeis4.)