A254705 Number of length 7+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.

334, 9106, 87892, 489135, 1954106, 6255136, 17080712, 41376909, 91273510, 186738046, 359115868, 655729243, 1145723346, 1927361900, 3136990096, 4959897305, 7643326974, 11511895978, 16985700580, 24601401031, 35036591722

Offset

1,1

Links

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

Formula

Empirical: a(n) = (31/84)*n^8 + (323/35)*n^7 + (473/10)*n^6 + 94*n^5 + (967/12)*n^4 + (377/10)*n^3 + (7927/210)*n^2 + (365/14)*n + 1.

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

G.f.: x*(334 + 6100*x + 17962*x^2 - 2133*x^3 - 6817*x^4 - 614*x^5 + 56*x^6 - 9*x^7 + x^8) / (1 - x)^9.

a(n) = 9*a(n-1) - 36*a(n-2) + 84*a(n-3) - 126*a(n-4) + 126*a(n-5) - 84*a(n-6) + 36*a(n-7) - 9*a(n-8) + a(n-9) for n>9.

(End)

Example

Some solutions for n=3:
..3....1....0....2....1....1....0....2....3....0....2....1....3....2....3....1
..2....2....1....1....0....0....3....1....1....1....0....3....1....2....2....1
..0....1....1....1....1....3....3....2....0....1....1....1....1....1....3....1
..2....2....2....0....1....1....0....0....1....0....3....1....2....1....1....2
..2....0....1....3....3....1....0....1....3....0....1....3....1....1....2....1
..2....1....1....2....1....2....0....3....1....0....1....0....1....1....2....0
..3....1....3....1....2....1....0....1....3....0....1....2....2....1....3....1
..2....2....1....1....0....2....1....2....0....3....1....1....1....0....2....1
..2....1....1....1....1....1....0....1....1....2....2....1....3....3....1....3
..2....1....0....0....3....1....3....0....1....0....2....2....1....1....2....3
..0....0....3....2....1....1....0....1....2....0....1....0....0....3....2....0

Crossrefs

Row 7 of A254698.

Sequence in context: A182098 A331411 A020367 * A184463 A303210 A278098

Adjacent sequences: A254702 A254703 A254704 * A254706 A254707 A254708

Keyword

nonn

Author

R. H. Hardin, Feb 05 2015

Status

approved