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A250017 Number of length 3+5 0..n arrays with no six consecutive terms having the maximum of any three terms equal to the minimum of the remaining three terms. 1
20, 912, 13512, 106352, 558588, 2224848, 7259024, 20384352, 50937444, 115954256, 244606296, 484335696, 909078092, 1630002576, 2809238304, 4677097664, 7553346228, 11873110032, 18218051048, 27353482032, 40272132252, 58245315920 (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) = n^8 + (41/35)*n^7 + (56/15)*n^6 + (22/5)*n^5 + (19/3)*n^4 + (17/5)*n^3 - (16/15)*n^2 + (36/35)*n.

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

G.f.: 4*x*(5 + 183*x + 1506*x^2 + 3974*x^3 + 3441*x^4 + 903*x^5 + 68*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>8.

(End)

EXAMPLE

Some solutions for n=4:

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

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

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

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

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

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

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

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

CROSSREFS

Row 3 of A250014.

Sequence in context: A192370 A113102 A285673 * A305116 A066802 A066798

Adjacent sequences:  A250014 A250015 A250016 * A250018 A250019 A250020

KEYWORD

nonn

AUTHOR

R. H. Hardin, Nov 10 2014

STATUS

approved

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Last modified April 14 01:49 EDT 2021. Contains 342941 sequences. (Running on oeis4.)