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A255108 Number of length n+1 0..2 arrays with at most one downstep in every n consecutive neighbor pairs. 1
9, 26, 66, 147, 294, 540, 927, 1507, 2343, 3510, 5096, 7203, 9948, 13464, 17901, 23427, 30229, 38514, 48510, 60467, 74658, 91380, 110955, 133731, 160083, 190414, 225156, 264771, 309752, 360624, 417945, 482307, 554337, 634698, 724090, 823251, 932958 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,1
COMMENTS
Row 1 of A255107.
LINKS
FORMULA
Empirical: a(n) = (1/120)*n^5 + (1/6)*n^4 + (19/24)*n^3 + (11/6)*n^2 + (16/5)*n + 3.
Empirical g.f.: x*(9 - 28*x + 45*x^2 - 39*x^3 + 17*x^4 - 3*x^5) / (1 - x)^6. - Colin Barker, Jan 24 2018
EXAMPLE
Some solutions for n=4:
..1....1....0....0....0....1....0....0....1....2....0....0....1....1....0....0
..1....2....0....0....0....1....1....1....1....1....2....2....2....0....0....0
..0....0....2....2....1....2....0....1....1....2....2....2....2....0....2....2
..0....2....1....0....1....2....0....2....1....2....2....1....0....0....2....0
..1....2....1....2....2....1....1....1....2....2....0....2....2....0....1....1
CROSSREFS
Cf. A255107.
Sequence in context: A249275 A270695 A048468 * A048771 A055849 A235163
KEYWORD
nonn
AUTHOR
R. H. Hardin, Feb 14 2015
STATUS
approved

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Last modified May 17 19:53 EDT 2024. Contains 372607 sequences. (Running on oeis4.)