A267473 Number of length-5 0..n arrays with no following elements larger than the first repeated value.

21, 160, 712, 2285, 5921, 13216, 26440, 48657, 83845, 137016, 214336, 323245, 472577, 672680, 935536, 1274881, 1706325, 2247472, 2918040, 3739981, 4737601, 5937680, 7369592, 9065425, 11060101, 13391496, 16100560, 19231437, 22831585

Offset

1,1

Comments

Row 5 of A267471.

Links

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

Formula

Empirical: a(n) = n^5 + (37/12)*n^4 + (11/2)*n^3 + (77/12)*n^2 + 4*n + 1.

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

G.f.: x*(21 + 34*x + 67*x^2 - 7*x^3 + 6*x^4 - x^5) / (1 - x)^6.

a(n) = 6*a(n-1) - 15*a(n-2) + 20*a(n-3) - 15*a(n-4) + 6*a(n-5) - a(n-6) for n>6.

(End)

Example

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

Crossrefs

Cf. A267471.

Sequence in context: A180374 A108675 A296832 * A179097 A070315 A242191

Adjacent sequences: A267470 A267471 A267472 * A267474 A267475 A267476

Keyword

nonn

Author

R. H. Hardin, Jan 15 2016

Status

approved