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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. 1
354, 8377, 79740, 455055, 1879526, 6219899, 17519352, 43657365, 98808010, 206916501, 406440244, 756627027, 1345629390, 2300780615, 3801384176, 6094394889, 9513396402, 14501306065, 21637264620, 31668194551, 45545537334 (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) = (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: A251127 A176197 A157668 * A293563 A241960 A221450

Adjacent sequences:  A250154 A250155 A250156 * A250158 A250159 A250160

KEYWORD

nonn

AUTHOR

R. H. Hardin, Nov 13 2014

STATUS

approved

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Last modified December 6 13:24 EST 2021. Contains 349563 sequences. (Running on oeis4.)