A269490 Number of length-n 0..4 arrays with no repeated value differing from the previous repeated value by one.

5, 25, 125, 617, 3021, 14695, 71115, 342749, 1646513, 7888637, 37714065, 179987481, 857744605, 4082846423, 19415519707, 92255164553, 438075822317, 2079098651337, 9863010567565, 46772069428089, 221735120808989, 1050936378053663

Offset

1,1

Links

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

Formula

Empirical: a(n) = 12*a(n-1) - 43*a(n-2) + 24*a(n-3) + 75*a(n-4) + 20*a(n-5) - a(n-6).

Empirical g.f.: x*(5 - 35*x + 40*x^2 + 72*x^3 + 17*x^4 - x^5) / (1 - 12*x + 43*x^2 - 24*x^3 - 75*x^4 - 20*x^5 + x^6). - Colin Barker, Jan 23 2019

Example

Some solutions for n=6:
..4. .0. .2. .2. .3. .4. .2. .2. .0. .3. .0. .4. .2. .0. .2. .0
..2. .3. .0. .4. .2. .1. .1. .3. .4. .2. .0. .0. .4. .2. .0. .0
..0. .0. .4. .1. .1. .3. .4. .3. .0. .1. .0. .3. .4. .1. .0. .2
..3. .0. .2. .1. .2. .2. .1. .3. .1. .1. .0. .3. .3. .4. .3. .2
..0. .4. .3. .0. .1. .0. .3. .1. .1. .0. .3. .0. .4. .3. .0. .4
..1. .1. .2. .1. .4. .3. .1. .4. .0. .3. .1. .4. .0. .1. .0. .1

Crossrefs

Column 4 of A269494.

Sequence in context: A269579 A269431 A269686 * A269772 A269652 A163844

Adjacent sequences: A269487 A269488 A269489 * A269491 A269492 A269493

Keyword

nonn

Author

R. H. Hardin, Feb 28 2016

Status

approved