A269471 Number of length-7 0..n arrays with no repeated value equal to the previous repeated value.

30, 1206, 11796, 63420, 242370, 741090, 1934856, 4488696, 9499590, 18678990, 34580700, 60879156, 102703146, 167030010, 263145360, 403173360, 602682606, 881372646, 1263846180, 1780471980, 2468343570, 3372338706, 4546284696

Offset

1,1

Links

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

Formula

Empirical: a(n) = n^7 + 7*n^6 + 16*n^5 + 8*n^4 - n^3 - n.

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

G.f.: 6*x*(5 + 161*x + 498*x^2 + 190*x^3 - 23*x^4 + 9*x^5) /(1 - x)^8.

a(n) = 8*a(n-1) - 28*a(n-2) + 56*a(n-3) - 70*a(n-4) + 56*a(n-5) - 28*a(n-6) + 8*a(n-7) - a(n-8) for n>8.

(End)

Example

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

Crossrefs

Row 7 of A269467.

Sequence in context: A214820 A259462 A269682 * A060076 A174716 A163521

Adjacent sequences: A269468 A269469 A269470 * A269472 A269473 A269474

Keyword

nonn

Author

R. H. Hardin, Feb 27 2016

Status

approved