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A267472 Number of length-4 0..n arrays with no following elements larger than the first repeated value. 1
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 (list; graph; refs; listen; history; text; internal format)
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

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Last modified February 2 03:35 EST 2023. Contains 359997 sequences. (Running on oeis4.)