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A254699 Number of length 1+4 0..n arrays with every five consecutive terms having the maximum of some two terms equal to the minimum of the remaining three terms. 1
22, 133, 464, 1205, 2606, 4977, 8688, 14169, 21910, 32461, 46432, 64493, 87374, 115865, 150816, 193137, 243798, 303829, 374320, 456421, 551342, 660353, 784784, 926025, 1085526, 1264797, 1465408, 1688989, 1937230, 2211881, 2514752, 2847713 (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) = (5/2)*n^4 + (20/3)*n^3 + (15/2)*n^2 + (13/3)*n + 1.

Conjectures from Colin Barker, Dec 17 2018: (Start)

G.f.: x*(22 + 23*x + 19*x^2 - 5*x^3 + x^4) / (1 - x)^5.

a(n) = 5*a(n-1) - 10*a(n-2) + 10*a(n-3) - 5*a(n-4) + a(n-5) for n>5.

(End)

EXAMPLE

Some solutions for n=10:

..4....6....1....5...10....4....6....6....2....0....3....2....0....2....8....9

..9....9....1....9....6....4....9....7....0....9....3....7...10...10....9....4

..5....6....1....0....4....3....5....6....2...10....3....1....4....8....9....9

..4....0....4....5...10....2....5....0....9....9....2....2....6....5....8....0

..2...10....3....8....6....3....3....9....7....9....3....4....4....5....6....4

CROSSREFS

Row 1 of A254698.

Sequence in context: A003778 A254698 A041936 * A183909 A263481 A238170

Adjacent sequences:  A254696 A254697 A254698 * A254700 A254701 A254702

KEYWORD

nonn

AUTHOR

R. H. Hardin, Feb 05 2015

STATUS

approved

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Last modified October 20 04:37 EDT 2019. Contains 328247 sequences. (Running on oeis4.)