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A249961 Number of length 1+5 0..n arrays with no six consecutive terms having the maximum of any two terms equal to the minimum of the remaining four terms. 1
15, 285, 2010, 8790, 28785, 77595, 181860, 383580, 745155, 1355145, 2334750, 3845010, 6094725, 9349095, 13939080, 20271480, 28839735, 40235445, 55160610, 74440590, 99037785, 130066035, 168805740, 216719700, 275469675, 346933665 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Row 1 of A249960.

LINKS

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

FORMULA

Empirical: a(n) = n^6 + 3*n^5 + 5*n^4 + 5*n^3 + (3/2)*n^2 - (1/2)*n.

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

G.f.: 15*x*(1 + x)^2*(1 + 10*x + x^2) / (1 - x)^7.

a(n) = 7*a(n-1) - 21*a(n-2) + 35*a(n-3) - 35*a(n-4) + 21*a(n-5) - 7*a(n-6) + a(n-7) for n>7.

(End)

EXAMPLE

Some solutions for n=6:

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

..3....4....1....2....4....5....1....2....3....3....1....2....1....6....0....3

..3....5....3....5....3....5....3....0....6....5....0....4....6....4....3....4

..5....3....1....3....0....6....2....3....6....2....2....1....5....1....6....1

..0....2....3....5....4....5....3....1....0....5....4....1....1....3....1....6

..4....0....2....1....4....3....3....6....1....0....3....2....2....5....3....4

CROSSREFS

Sequence in context: A095654 A279167 A249960 * A177074 A069405 A125055

Adjacent sequences:  A249958 A249959 A249960 * A249962 A249963 A249964

KEYWORD

nonn

AUTHOR

R. H. Hardin, Nov 09 2014

STATUS

approved

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Last modified December 4 19:40 EST 2021. Contains 349526 sequences. (Running on oeis4.)