A250354 Number of length 5 arrays x(i), i=1..5 with x(i) in i..i+n and no value appearing more than 2 times.

32, 216, 888, 2724, 6900, 15186, 30072, 54888, 93924, 152550, 237336, 356172, 518388, 734874, 1018200, 1382736, 1844772, 2422638, 3136824, 4010100, 5067636, 6337122, 7848888, 9636024, 11734500, 14183286, 17024472, 20303388, 24068724

Offset

1,1

Links

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

Formula

Empirical: a(n) = n^5 + 5*n^4 + 25*n^2 + 5*n for n>2.

Conjectures from Colin Barker, Nov 13 2018: (Start)

G.f.: 2*x*(16 + 12*x + 36*x^2 - 2*x^3 + 18*x^4 - 33*x^5 + 16*x^6 - 3*x^7) / (1 - x)^6.

a(n) = 6*a(n-1) - 15*a(n-2) + 20*a(n-3) - 15*a(n-4) + 6*a(n-5) - a(n-6) for n>8.

(End)

Example

Some solutions for n=6:
..3....1....2....0....3....1....5....1....2....5....6....4....2....6....3....1
..4....5....1....4....6....1....1....2....2....2....1....1....7....1....1....7
..2....8....3....7....4....4....2....7....5....6....3....2....5....8....5....2
..3....8....8....8....8....4....4....7....5....3....8....9....3....5....6....7
.10....6....6....8....9....7....6....6....9....7....5....5....9....5....7....9

Crossrefs

Row 5 of A250351.

Sequence in context: A126500 A160538 A200787 * A183778 A146089 A250232

Adjacent sequences: A250351 A250352 A250353 * A250355 A250356 A250357

Keyword

nonn

Author

R. H. Hardin, Nov 19 2014

Status

approved