A267233 Number of length-4 0..n arrays with no following elements greater than or equal to the first repeated value.

6, 47, 176, 470, 1030, 1981, 3472, 5676, 8790, 13035, 18656, 25922, 35126, 46585, 60640, 77656, 98022, 122151, 150480, 183470, 221606, 265397, 315376, 372100, 436150, 508131, 588672, 678426, 778070, 888305, 1009856, 1143472, 1289926

Offset: 1

Author

R. H. Hardin, Jan 12 2016

Keywords

• nonn

Comments

Row 4 of A267232.

Examples

			Some solutions for n=6:
..4....5....2....2....0....4....4....5....0....4....3....2....0....4....0....3
..3....3....4....0....5....2....0....6....3....5....4....4....3....3....2....6
..1....3....2....5....5....3....1....2....5....5....2....1....0....2....4....4
..4....0....6....4....4....1....4....1....4....3....3....3....6....4....2....6
		

Links

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

Crossrefs

Cf. A267232.

Formula

Empirical: a(n) = n^4 + (17/6)*n^3 + 2*n^2 + (1/6)*n.

Conjectures from Colin Barker, Feb 05 2018: (Start)

G.f.: x*(6 + 17*x + x^2) / (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)