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A255663 Number of length n+3 0..3 arrays with at most two downsteps in every n consecutive neighbor pairs 1
256, 1024, 4048, 14192, 42653, 112196, 265430, 577464, 1174730, 2262312, 4162792, 7370432, 12625472, 21014456, 34103820, 54115508, 84155145, 128505312, 192998760, 285488992, 416438559, 599648684, 853157474, 1200338032, 1671232268 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Row 3 of A255660

LINKS

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

FORMULA

Empirical: a(n) = (1/39916800)*n^11 + (1/403200)*n^10 + (1/9072)*n^9 + (109/40320)*n^8 + (63421/1209600)*n^7 + (39319/57600)*n^6 + (1888387/362880)*n^5 + (24707/2240)*n^4 + (4099087/453600)*n^3 + (33487/525)*n^2 + (950843/6930)*n + 28 for n>1

EXAMPLE

Some solutions for n=4

..3....3....0....0....1....1....2....0....2....3....1....0....3....1....3....3

..1....1....0....0....0....0....2....1....2....2....2....0....0....0....3....2

..3....2....3....1....3....1....2....3....0....2....1....2....3....1....0....0

..0....0....2....1....3....2....2....3....0....1....1....1....3....1....0....0

..0....2....2....3....3....1....2....3....3....3....0....3....1....3....1....2

..0....3....2....1....2....1....0....1....1....3....1....3....0....1....1....2

..3....1....2....3....3....2....1....2....0....1....2....3....1....1....2....2

CROSSREFS

Cf. A255660

Sequence in context: A220764 A135272 A205595 * A045034 A236911 A236904

Adjacent sequences:  A255660 A255661 A255662 * A255664 A255665 A255666

KEYWORD

nonn

AUTHOR

R. H. Hardin, Mar 01 2015

STATUS

approved

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Last modified November 28 09:55 EST 2021. Contains 349401 sequences. (Running on oeis4.)