A255629 Number of length n+7 0..2 arrays with at most two downsteps in every n consecutive neighbor pairs

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

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

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

Cf. A255622

Sequence in context: A046321 A043456 A255114 * A017080 A017164 A017380

Adjacent sequences: A255626 A255627 A255628 * A255630 A255631 A255632

Keyword

nonn

Author

R. H. Hardin, Feb 28 2015

Status

approved