A254699 Number of length 1+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.

22, 133, 464, 1205, 2606, 4977, 8688, 14169, 21910, 32461, 46432, 64493, 87374, 115865, 150816, 193137, 243798, 303829, 374320, 456421, 551342, 660353, 784784, 926025, 1085526, 1264797, 1465408, 1688989, 1937230, 2211881, 2514752, 2847713

Offset

1,1

Links

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

Formula

Empirical: a(n) = (5/2)*n^4 + (20/3)*n^3 + (15/2)*n^2 + (13/3)*n + 1.

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

G.f.: x*(22 + 23*x + 19*x^2 - 5*x^3 + x^4) / (1 - x)^5.

a(n) = 5*a(n-1) - 10*a(n-2) + 10*a(n-3) - 5*a(n-4) + a(n-5) for n>5.

(End)

Example

Some solutions for n=10:
..4....6....1....5...10....4....6....6....2....0....3....2....0....2....8....9
..9....9....1....9....6....4....9....7....0....9....3....7...10...10....9....4
..5....6....1....0....4....3....5....6....2...10....3....1....4....8....9....9
..4....0....4....5...10....2....5....0....9....9....2....2....6....5....8....0
..2...10....3....8....6....3....3....9....7....9....3....4....4....5....6....4

Crossrefs

Row 1 of A254698.

Sequence in context: A003778 A254698 A041936 * A183909 A263481 A238170

Adjacent sequences: A254696 A254697 A254698 * A254700 A254701 A254702

Keyword

nonn

Author

R. H. Hardin, Feb 05 2015

Status

approved