A269674 Number of length-n 0..4 arrays with no repeated value differing from the previous repeated value by other than plus or minus one modulo 4+1.

5, 25, 120, 570, 2670, 12390, 57030, 260790, 1185990, 5368470, 24204390, 108756150, 487223430, 2177121750, 9706364070, 43188455670, 191830083270, 850727111190, 3767586342630, 16664819732790, 73630769405190, 325004395216470

Offset

1,1

Links

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

Formula

Empirical: a(n) = 7*a(n-1) - 6*a(n-2) - 24*a(n-3).

Empirical g.f.: 5*x*(1 - 2*x - 5*x^2) / ((1 - 4*x)*(1 - 3*x - 6*x^2)). - Colin Barker, Jan 26 2019

Example

Some solutions for n=7:
..0. .0. .3. .1. .4. .4. .3. .1. .1. .4. .1. .4. .0. .1. .0. .0
..0. .2. .1. .4. .3. .1. .3. .0. .4. .3. .3. .3. .1. .2. .4. .1
..3. .1. .3. .3. .2. .2. .0. .2. .3. .1. .1. .3. .3. .4. .0. .3
..4. .0. .3. .3. .2. .1. .4. .0. .3. .2. .4. .4. .4. .0. .4. .2
..4. .3. .4. .1. .0. .3. .4. .1. .1. .2. .4. .3. .0. .1. .4. .2
..3. .1. .0. .4. .2. .0. .2. .0. .0. .0. .0. .1. .1. .1. .0. .1
..3. .3. .1. .1. .4. .2. .3. .1. .1. .2. .0. .4. .4. .0. .0. .4

Crossrefs

Column 4 of A269678.

Sequence in context: A269636 A269533 A269405 * A269602 A089927 A269463

Adjacent sequences: A269671 A269672 A269673 * A269675 A269676 A269677

Keyword

nonn

Author

R. H. Hardin, Mar 03 2016

Status

approved