A258736 Number of length n+6 0..3 arrays with at most one downstep in every n consecutive neighbor pairs.

16384, 43681, 68120, 98676, 149960, 228081, 331584, 465580, 635992, 849708, 1114752, 1440474, 1837760, 2319263, 2899656, 3595908, 4427584, 5417170, 6590424, 7976754, 9609624, 11526989, 13771760, 16392300, 19442952, 22984600, 27085264

Offset

1,1

Comments

Row 6 of A258730.

Links

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

Formula

Empirical: a(n) = (1/5040)*n^7 + (1/72)*n^6 + (149/360)*n^5 + (239/36)*n^4 + (297247/720)*n^3 + (187297/72)*n^2 + (178036/35)*n + 2212 for n>4.

Empirical g.f.: x*(16384 - 87391*x + 177424*x^2 - 140720*x^3 - 31344*x^4 + 116775*x^5 - 39024*x^6 - 13988*x^7 - 31192*x^8 + 58867*x^9 - 31680*x^10 + 5890*x^11) / (1 - x)^8. - Colin Barker, Jan 26 2018

Example

Some solutions for n=4:
..2....1....1....2....0....0....2....1....3....0....2....1....0....3....0....0
..2....0....1....0....0....0....0....1....3....1....1....1....2....3....0....0
..0....1....2....0....2....2....0....0....2....0....1....2....3....0....2....3
..0....1....0....0....2....2....0....1....2....0....3....0....3....0....2....0
..2....1....0....0....2....0....0....2....2....3....3....2....1....0....0....0
..2....2....0....1....2....0....2....2....2....3....1....2....1....0....0....1
..3....3....2....2....2....0....0....3....0....0....1....2....1....1....0....3
..1....3....1....2....0....0....1....3....2....0....1....0....2....3....1....3
..3....3....1....3....2....1....2....1....2....3....3....0....3....1....2....0
..3....2....1....0....3....0....2....1....3....3....1....0....2....1....3....0

Crossrefs

Cf. A258730.

Sequence in context: A212936 A069275 A216074 * A255666 A220767 A115348

Adjacent sequences: A258733 A258734 A258735 * A258737 A258738 A258739

Keyword

nonn

Author

R. H. Hardin, Jun 08 2015

Status

approved