A269775 Number of length-n 0..7 arrays with every repeated value unequal to the previous repeated value plus one mod 7+1.

8, 64, 512, 4088, 32592, 259504, 2063880, 16398144, 130175360, 1032602872, 8185566032, 64850011184, 513508842504, 4064330589760, 32155606323456, 254314670475768, 2010717722177360, 15893207240651440, 125593338184358408

Offset: 1

Author

R. H. Hardin, Mar 04 2016

Keywords

• nonn

Examples

			Some solutions for n=5:
..4. .2. .0. .1. .2. .0. .2. .7. .4. .3. .1. .0. .7. .5. .5. .6
..3. .3. .0. .1. .2. .5. .0. .1. .7. .1. .0. .5. .1. .2. .1. .6
..4. .2. .6. .0. .6. .5. .0. .1. .1. .5. .3. .2. .5. .6. .7. .6
..3. .0. .1. .4. .4. .1. .7. .5. .3. .3. .3. .4. .3. .1. .1. .5
..5. .1. .5. .1. .0. .4. .5. .5. .0. .1. .3. .0. .1. .1. .2. .7
		

Links

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

Crossrefs

Column 7 of A269776.

Formula

Empirical: a(n) = 14*a(n-1) - 42*a(n-2) -49*a(n-3).

Empirical g.f.: 8*x*(1 - 6*x - 6*x^2) / ((1 - 7*x)*(1 - 7*x - 7*x^2)). - Colin Barker, Jan 29 2019