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A189324 Number of nondecreasing arrangements of n+2 numbers in 0..7 with the last equal to 7 and each after the second equal to the sum of one or two of the preceding four. 1
11, 17, 31, 51, 91, 157, 253, 374, 509, 649, 789, 929, 1069, 1209, 1349, 1489, 1629, 1769, 1909, 2049, 2189, 2329, 2469, 2609, 2749, 2889, 3029, 3169, 3309, 3449, 3589, 3729, 3869, 4009, 4149, 4289, 4429, 4569, 4709, 4849, 4989, 5129, 5269, 5409, 5549 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Column 7 of A189326.

LINKS

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

FORMULA

Empirical: a(n) = 140*n - 751 for n>8.

Empirical g.f.: x*(11 - 5*x + 8*x^2 + 6*x^3 + 20*x^4 + 26*x^5 + 30*x^6 + 25*x^7 + 14*x^8 + 5*x^9) / (1 - x)^2. - Colin Barker, May 02 2018

EXAMPLE

Some solutions for n=3:

..1....7....2....2....1....3....3....1....1....3....1....1....1....4....1....1

..4....7....5....5....3....4....4....3....3....7....6....3....5....7....2....5

..5....7....5....5....4....7....4....4....3....7....7....4....6....7....3....6

..6....7....5....7....7....7....7....5....4....7....7....4....6....7....5....7

..7....7....7....7....7....7....7....7....7....7....7....7....7....7....7....7

CROSSREFS

Cf. A189326.

Sequence in context: A208573 A142718 A258866 * A127703 A165667 A339180

Adjacent sequences:  A189321 A189322 A189323 * A189325 A189326 A189327

KEYWORD

nonn

AUTHOR

R. H. Hardin, Apr 20 2011

STATUS

approved

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Last modified June 24 22:23 EDT 2021. Contains 345445 sequences. (Running on oeis4.)