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A250391 Number of length 5+3 0..n arrays with no four consecutive terms having the maximum of any two terms equal to the minimum of the remaining two terms. 1
6, 514, 9480, 82398, 457366, 1886948, 6308960, 18038628, 45704886, 105193902, 223903240, 446650386, 843619686, 1520772064, 2633182208, 4401808232, 7134239142, 11250005754, 17311081032, 26058236134, 38453958774, 55732680828 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Row 5 of A250387.

LINKS

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

FORMULA

Empirical: a(n) = n^8 + (1/5)*n^7 + (563/180)*n^6 + (19/30)*n^5 + (1/9)*n^4 + (9/5)*n^3 - (223/180)*n^2 + (11/30)*n.

Conjectures from Colin Barker, Aug 21 2017: (Start)

G.f.: 2*x*(3 + 230*x + 2535*x^2 + 7539*x^3 + 7322*x^4 + 2335*x^5 + 196*x^6) / (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=4:

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

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

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

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

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

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

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

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

CROSSREFS

Sequence in context: A103520 A223050 A290937 * A003395 A222607 A000411

Adjacent sequences:  A250388 A250389 A250390 * A250392 A250393 A250394

KEYWORD

nonn

AUTHOR

R. H. Hardin, Nov 20 2014

STATUS

approved

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Last modified November 20 08:16 EST 2018. Contains 317385 sequences. (Running on oeis4.)