A269618 Number of length-n 0..7 arrays with no repeated value differing from the previous repeated value by other than plus two, zero or minus 1.

8, 64, 512, 4053, 31822, 248143, 1923796, 14840928, 113998742, 872397577, 6654286340, 50608816911, 383908730032, 2905532655620, 21944295375268, 165426094919204, 1244944198391978, 9354631892435631, 70193014149728040

Offset

1,1

Comments

Column 7 of A269619.

Links

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

Formula

Empirical: a(n) = 63*a(n-1) -1756*a(n-2) +28364*a(n-3) -291578*a(n-4) +1965390*a(n-5) -8566706*a(n-6) +22451548*a(n-7) -27837343*a(n-8) -2892449*a(n-9) +25243250*a(n-10) +17146752*a(n-11) +6127748*a(n-12) +1523522*a(n-13) +264748*a(n-14) +31542*a(n-15) +2437*a(n-16) +91*a(n-17)

Example

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

Crossrefs

Cf. A269619.

Sequence in context: A228981 A222388 A222937 * A269582 A269434 A269689

Adjacent sequences: A269615 A269616 A269617 * A269619 A269620 A269621

Keyword

nonn

Author

R. H. Hardin, Mar 01 2016

Status

approved