A250357 Number of length n arrays x(i), i=1..n with x(i) in i..i+4 and no value appearing more than 3 times.

5, 25, 125, 623, 3094, 15365, 76300, 378880, 1881364, 9342081, 46388915, 230348138, 1143813376, 5679703079, 28203050974, 140044659409, 695403722139, 3453086599482, 17146596550508, 85142890221146, 422784296221329

Offset

1,1

Links

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

Formula

Empirical: a(n) = 5*a(n-1) - 2*a(n-4) - 11*a(n-5) + a(n-8).

Empirical g.f.: x*(5 - 2*x^3 - 11*x^4 + x^7) / (1 - 5*x + 2*x^4 + 11*x^5 - x^8). - Colin Barker, Nov 13 2018

Example

Some solutions for n=6:
..2....4....0....0....2....2....0....2....0....1....3....3....4....1....2....0
..4....3....4....2....2....3....2....3....4....1....2....1....4....1....5....3
..2....5....5....5....6....6....4....6....3....2....2....5....5....5....6....6
..4....6....7....6....3....5....5....4....7....4....4....7....4....4....7....3
..8....7....4....5....5....8....6....4....7....7....5....6....6....8....6....8
..7....9....9....6....5....7....7....8....6....5....5....7....6....5....8....9

Crossrefs

Column 4 of A250361.

Sequence in context: A269772 A269652 A163844 * A216125 A057831 A014946

Adjacent sequences: A250354 A250355 A250356 * A250358 A250359 A250360

Keyword

nonn

Author

R. H. Hardin, Nov 19 2014

Status

approved