A269649 Number of length-n 0..n arrays with no adjacent pair x,x+1 repeated.

2, 9, 64, 621, 7686, 115902, 2061940, 42277329, 981592964, 25455321375, 729233710320, 22870710513322, 779384544768952, 28676004488510379, 1132947222095403840, 47837636065465105365, 2149808857973618974752

Offset

1,1

Comments

Diagonal of A269656.

Links

R. H. Hardin, Table of n, a(n) for n = 1..20

Example

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

Crossrefs

Cf. A269656.

Sequence in context: A036775 A141209 A269770 * A335517 A128577 A052514

Adjacent sequences: A269646 A269647 A269648 * A269650 A269651 A269652

Keyword

nonn

Author

R. H. Hardin, Mar 02 2016

Status

approved