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A250340 Number of length 4+5 0..n arrays with every six consecutive terms having the maximum of some three terms equal to the minimum of the remaining three terms. 1
172, 4409, 37824, 193437, 725596, 2210213, 5794496, 13561449, 29037004, 57870241, 108719744, 194381733, 333198204, 550785901, 882129536, 1374085265, 2088343020, 3104898889, 4526091328, 6481257581, 9132069276, 12678608757, 17366250304 (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) = (9/140)*n^8 + (27/10)*n^7 + 19*n^6 + 48*n^5 + (1203/20)*n^4 + (1189/30)*n^3 + (81/14)*n^2 - (13/3)*n + 1.

Conjectures from Colin Barker, Nov 12 2018: (Start)

G.f.: x*(172 + 2861*x + 4335*x^2 - 2703*x^3 - 2357*x^4 + 227*x^5 + 65*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=4:

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

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

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

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

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

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

..2....2....2....2....4....2....1....4....1....1....2....2....2....2....1....2

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

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

CROSSREFS

Row 4 of A250336.

Sequence in context: A214115 A250968 A264213 * A035828 A259017 A097845

Adjacent sequences:  A250337 A250338 A250339 * A250341 A250342 A250343

KEYWORD

nonn

AUTHOR

R. H. Hardin, Nov 19 2014

STATUS

approved

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Last modified December 10 04:15 EST 2019. Contains 329885 sequences. (Running on oeis4.)