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A250339 Number of length 3+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
108, 1989, 14040, 62041, 206724, 569693, 1369136, 2966769, 5927452, 11092917, 19671048, 33342153, 54383668, 85814733, 131562080, 196648673, 287406540, 411715237, 579267384, 801862713, 1093732068, 1471892797, 1956536976 (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) = (2/7)*n^7 + (28/5)*n^6 + (112/5)*n^5 + (109/3)*n^4 + (94/3)*n^3 + (166/15)*n^2 - (2/105)*n + 1.

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

G.f.: x*(108 + 1125*x + 1152*x^2 - 635*x^3 - 308*x^4 - 9*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....2....0....2....2....0....0....1....4....3....4....4....3....2....0....3

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

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

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

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

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

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

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

CROSSREFS

Row 3 of A250336.

Sequence in context: A279981 A233317 A263970 * A263961 A202427 A063809

Adjacent sequences:  A250336 A250337 A250338 * A250340 A250341 A250342

KEYWORD

nonn

AUTHOR

R. H. Hardin, Nov 19 2014

STATUS

approved

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Last modified July 1 13:12 EDT 2022. Contains 354973 sequences. (Running on oeis4.)