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A255629
Number of length n+7 0..2 arrays with at most two downsteps in every n consecutive neighbor pairs
1
6561, 19683, 59049, 152106, 322078, 602886, 1047141, 1706242, 2653107, 3977859, 5790140, 8221629, 11428785, 15595837, 20938044, 27705249, 36185752, 46710528, 59657817, 75458114, 94599588, 117633960, 145182871, 177944772, 216702369
OFFSET
1,1
COMMENTS
Row 7 of A255622
LINKS
FORMULA
Empirical: a(n) = (1/40320)*n^8 + (23/10080)*n^7 + (239/2880)*n^6 + (1541/144)*n^5 + (920887/5760)*n^4 + (442121/1440)*n^3 + (42883817/3360)*n^2 - (2307073/56)*n + 29319 for n>5
EXAMPLE
Some solutions for n=4
..1....2....0....2....1....1....2....2....2....1....0....2....0....0....0....1
..1....0....1....0....0....0....0....0....0....0....0....0....2....1....0....1
..1....0....2....0....1....0....0....1....0....1....1....0....0....0....0....1
..2....0....1....2....2....2....1....1....0....2....2....1....2....2....1....1
..0....1....1....2....1....2....2....1....0....1....1....2....0....1....1....1
..2....2....2....0....2....0....0....1....0....0....0....0....2....2....0....1
..1....1....0....0....0....2....0....2....2....2....2....0....0....2....2....2
..2....1....2....1....0....0....2....0....0....2....2....0....0....2....2....0
..2....0....1....1....0....1....0....1....2....2....0....0....1....2....2....2
..2....2....2....2....0....1....0....1....2....2....1....0....2....0....2....2
..1....0....1....0....0....0....1....1....0....0....0....1....2....2....1....2
CROSSREFS
Sequence in context: A046321 A043456 A255114 * A017080 A017164 A017380
KEYWORD
nonn
AUTHOR
R. H. Hardin, Feb 28 2015
STATUS
approved