A269470 Number of length-6 0..n arrays with no repeated value equal to the previous repeated value.

22, 462, 3180, 13300, 41730, 108402, 246232, 505800, 960750, 1713910, 2904132, 4713852, 7377370, 11189850, 16517040, 23805712, 33594822, 46527390, 63363100, 84991620, 112446642, 146920642, 189780360, 242583000, 307093150, 385300422

Offset

1,1

Links

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

Formula

Empirical: a(n) = n^6 + 6*n^5 + 11*n^4 + 4*n^3 - n^2 + n.

Conjectures from Colin Barker, Jan 23 2019: (Start)

G.f.: 2*x*(11 + 154*x + 204*x^2 - 14*x^3 + 5*x^4) / (1 - x)^7.

a(n) = 7*a(n-1) - 21*a(n-2) + 35*a(n-3) - 35*a(n-4) + 21*a(n-5) - 7*a(n-6) + a(n-7) for n>7.

(End)

Example

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

Crossrefs

Row 6 of A269467.

Sequence in context: A268460 A231659 A269681 * A162808 A212335 A342887

Adjacent sequences: A269467 A269468 A269469 * A269471 A269472 A269473

Keyword

nonn

Author

R. H. Hardin, Feb 27 2016

Status

approved