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A190040 Number of nondecreasing arrangements of n+2 numbers in 0..8 with the last equal to 8 and each after the second equal to the sum of one or two of the preceding three. 1
13, 24, 40, 65, 105, 164, 246, 349, 472, 617, 786, 981, 1204, 1457, 1742, 2061, 2416, 2809, 3242, 3717, 4236, 4801, 5414, 6077, 6792, 7561, 8386, 9269, 10212, 11217, 12286, 13421, 14624, 15897, 17242, 18661, 20156, 21729, 23382, 25117, 26936, 28841 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Column 8 of A190041.

LINKS

R. H. Hardin, Table of n, a(n) for n = 1..200

FORMULA

Empirical: a(n) = (1/3)*n^3 + 2*n^2 + (50/3)*n - 83 for n>6.

Conjectures from Colin Barker, May 04 2018: (Start)

G.f.: x*(13 - 28*x + 22*x^2 - 3*x^3 + 2*x^4 - 2*x^5 - 6*x^7 + x^8 + 3*x^9) / (1 - x)^4.

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

(End)

EXAMPLE

Some solutions for n=3:

..1....2....6....0....0....0....1....2....3....2....1....2....8....3....2....1

..4....4....8....8....4....4....4....4....8....6....4....6....8....4....3....7

..4....4....8....8....4....4....4....4....8....6....4....8....8....4....5....8

..8....4....8....8....4....8....5....8....8....8....4....8....8....4....8....8

..8....8....8....8....8....8....8....8....8....8....8....8....8....8....8....8

CROSSREFS

Cf. A190041.

Sequence in context: A266912 A032607 A335973 * A081723 A189325 A053080

Adjacent sequences:  A190037 A190038 A190039 * A190041 A190042 A190043

KEYWORD

nonn

AUTHOR

R. H. Hardin, May 04 2011

STATUS

approved

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Last modified September 16 15:56 EDT 2021. Contains 347473 sequences. (Running on oeis4.)