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A250376 Number of length 3+6 0..n arrays with every seven consecutive terms having the maximum of some three terms equal to the minimum of the remaining four terms. 1
252, 7168, 69984, 396745, 1616636, 5272892, 14647808, 36038649, 80620540, 167049696, 324977632, 599664273, 1057895164, 1795425260, 2946189056, 4693534097, 7283752188, 11042199904, 16392317280, 23877870841, 34188764412 (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) = (3/7)*n^8 + (57/7)*n^7 + (141/4)*n^6 + (202/3)*n^5 + (147/2)*n^4 + 44*n^3 + (443/28)*n^2 + (137/21)*n + 1.

Conjectures from Colin Barker, Nov 13 2018: (Start)

G.f.: x*(252 + 4900*x + 14544*x^2 + 3769*x^3 - 5005*x^4 - 1252*x^5 + 80*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....2....1....3....1....1....0....3....3....0....3....1....0....0....0....3

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

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

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

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

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

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

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

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

CROSSREFS

Row 3 of A250373.

Sequence in context: A024018 A270853 A177301 * A329755 A109924 A281032

Adjacent sequences:  A250373 A250374 A250375 * A250377 A250378 A250379

KEYWORD

nonn

AUTHOR

R. H. Hardin, Nov 19 2014

STATUS

approved

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Last modified April 13 17:30 EDT 2021. Contains 342936 sequences. (Running on oeis4.)