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A250375 Number of length 2+6 0..n arrays with every seven consecutive terms having the maximum of some three terms equal to the minimum of the remaining four terms. 1
151, 3096, 24566, 119235, 428421, 1256106, 3179756, 7202421, 14952595, 28938316, 52861986, 92002391, 153670401, 247744830, 387294936, 589296041, 875444751, 1273080256, 1816218190, 2546703531, 3515489021, 4784045586, 6425911236 (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) = (9/7)*n^7 + (37/3)*n^6 + (65/2)*n^5 + 46*n^4 + (217/6)*n^3 + (97/6)*n^2 + (233/42)*n + 1.

Conjectures from Colin Barker, Nov 13 2018: (Start)

G.f.: x*(151 + 1888*x + 4026*x^2 + 939*x^3 - 417*x^4 - 114*x^5 + 8*x^6 - x^7) / (1 - x)^8.

a(n) = 8*a(n-1) - 28*a(n-2) + 56*a(n-3) - 70*a(n-4) + 56*a(n-5) - 28*a(n-6) + 8*a(n-7) - a(n-8) for n>8.

(End)

EXAMPLE

Some solutions for n=4:

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

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

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

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

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

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

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

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

CROSSREFS

Row 2 of A250373

Sequence in context: A340436 A211555 A143012 * A060889 A206362 A200934

Adjacent sequences:  A250372 A250373 A250374 * A250376 A250377 A250378

KEYWORD

nonn

AUTHOR

R. H. Hardin, Nov 19 2014

STATUS

approved

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Last modified May 15 18:26 EDT 2021. Contains 343920 sequences. (Running on oeis4.)