A267472 Number of length-4 0..n arrays with no following elements larger than the first repeated value.

12, 62, 204, 515, 1096, 2072, 3592, 5829, 8980, 13266, 18932, 26247, 35504, 47020, 61136, 78217, 98652, 122854, 151260, 184331, 222552, 266432, 316504, 373325, 437476, 509562, 590212, 680079, 779840, 890196, 1011872, 1145617, 1292204

Offset

1,1

Comments

Row 4 of A267471.

Links

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

Formula

Empirical: a(n) = n^4 + (17/6)*n^3 + 4*n^2 + (19/6)*n + 1.

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

G.f.: x*(12 + 2*x + 14*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=7:
..2....1....5....5....0....2....5....6....3....4....0....0....3....3....2....3
..6....5....2....5....6....4....2....0....6....5....6....3....0....2....5....4
..0....2....3....0....3....1....0....4....3....1....4....0....5....5....6....7
..1....7....1....0....7....1....3....7....5....0....3....0....2....5....4....4

Crossrefs

Cf. A267471.

Sequence in context: A177677 A045822 A065595 * A194487 A196312 A196285

Adjacent sequences: A267469 A267470 A267471 * A267473 A267474 A267475

Keyword

nonn

Author

R. H. Hardin, Jan 15 2016

Status

approved