A254702 Number of length 4+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.

86, 1140, 6808, 26759, 81390, 208114, 469376, 962541, 1831798, 3282224, 5596152, 9151987, 14445614, 22114542, 32964928, 48001625, 68461398, 95849452, 131979416, 179016927, 239526958, 316525034, 413532480, 534635845, 684550646, 868689576

Offset

1,1

Links

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

Formula

Empirical: a(n) = (1/35)*n^7 + (8/5)*n^6 + (56/5)*n^5 + 25*n^4 + (249/10)*n^3 + (77/5)*n^2 + (481/70)*n + 1.

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

G.f.: x*(86 + 452*x + 96*x^2 - 601*x^3 + 122*x^4 - 18*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=5:
..3....1....3....0....2....1....0....4....4....4....4....3....4....2....0....3
..3....0....2....4....3....5....5....1....0....5....1....1....0....2....4....3
..3....0....2....2....0....4....1....0....0....3....2....1....4....1....3....5
..5....0....3....2....5....3....5....1....0....3....1....0....0....0....0....3
..3....5....2....3....2....3....1....1....5....3....1....3....0....1....0....3
..3....3....2....1....2....1....0....1....0....3....3....1....0....3....0....3
..1....0....2....2....3....3....1....4....0....0....0....1....2....1....0....4
..5....0....4....4....0....4....2....2....1....5....2....3....1....2....0....2

Crossrefs

Row 4 of A254698.

Sequence in context: A128957 A258584 A034277 * A206615 A242092 A232859

Adjacent sequences: A254699 A254700 A254701 * A254703 A254704 A254705

Keyword

nonn

Author

R. H. Hardin, Feb 05 2015

Status

approved