A269615 Number of length-n 0..4 arrays with no repeated value differing from the previous repeated value by other than plus two, zero or minus 1.

5, 25, 125, 612, 2956, 14125, 66925, 314935, 1473779, 6865098, 31856590, 147352985, 679742085, 3128486473, 14370696813, 65902020548, 301787376436, 1380297559417, 6306497302225, 28787967919963, 131309246498679, 598532215284482

Offset: 1

Author

R. H. Hardin, Mar 01 2016

Keywords

• nonn

Examples

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

Links

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

Crossrefs

Column 4 of A269619.

Formula

Empirical: a(n) = 16*a(n-1) - 93*a(n-2) + 220*a(n-3) - 115*a(n-4) - 168*a(n-5) - 44*a(n-6) - 16*a(n-7).

Empirical g.f.: x*(5 - 55*x + 190*x^2 - 163*x^3 - 136*x^4 - 40*x^5 - 12*x^6) / ((1 - 4*x)*(1 - 12*x + 45*x^2 - 40*x^3 - 45*x^4 - 12*x^5 - 4*x^6)). - Colin Barker, Jan 25 2019