A254703 Number of length 5+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.

136, 2310, 16276, 72271, 242076, 670372, 1618264, 3520845, 7060672, 13259026, 23586828, 40097083, 65580724, 103747728, 159435376, 238845529, 349812792, 502105438, 707760964, 981458151, 1340927500, 1807401916, 2406109512

Offset

1,1

Links

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

Formula

Empirical: a(n) = (13/35)*n^7 + (13/2)*n^6 + 26*n^5 + 41*n^4 + (327/10)*n^3 + (39/2)*n^2 + (125/14)*n + 1.

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

G.f.: x*(136 + 1222*x + 1604*x^2 - 873*x^3 - 204*x^4 - 20*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:
..0....3....1....0....3....3....0....0....4....2....2....1....2....1....0....2
..3....2....3....4....1....3....2....3....3....2....1....3....3....4....2....1
..1....3....0....2....1....3....1....0....3....2....1....2....2....4....1....2
..1....1....0....3....2....3....3....0....3....3....1....2....0....1....4....1
..4....2....0....2....1....3....1....0....1....3....1....4....4....1....1....1
..0....3....1....2....3....0....1....0....4....2....3....2....2....1....0....0
..2....2....0....4....1....3....4....2....3....2....1....2....3....1....1....2
..1....3....0....2....1....3....1....0....4....2....0....3....2....4....1....1
..1....2....3....1....0....4....1....4....3....1....3....0....2....0....1....4

Crossrefs

Row 5 of A254698.

Sequence in context: A235190 A249985 A072897 * A333110 A250424 A251940

Adjacent sequences: A254700 A254701 A254702 * A254704 A254705 A254706

Keyword

nonn

Author

R. H. Hardin, Feb 05 2015

Status

approved