A268955 Number of length-n 0..7 arrays with no repeated value equal to the previous repeated value, with new values introduced in sequential order.

1, 2, 4, 12, 40, 154, 656, 3074, 15615, 85314, 497262, 3068890, 19899645, 134520386, 940841796, 6760952170, 49617422739, 370013347266, 2792665457338, 21266237427018, 163008076378489, 1255477313622210, 9703388630792784

Offset

1,2

Comments

Column 7 of A268956.

Links

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

Formula

Empirical: a(n) = 38*a(n-1) -593*a(n-2) +4702*a(n-3) -17263*a(n-4) -4158*a(n-5) +265149*a(n-6) -681270*a(n-7) -916836*a(n-8) +6212496*a(n-9) -2473032*a(n-10) -24948000*a(n-11) +25941088*a(n-12) +53418784*a(n-13) -73975984*a(n-14) -60452512*a(n-15) +93916672*a(n-16) +28869120*a(n-17) -45158400*a(n-18) for n>20

Example

Some solutions for n=8
..0. .0. .0. .0. .0. .0. .0. .0. .0. .0. .0. .0. .0. .0. .0. .0
..1. .0. .1. .0. .1. .1. .0. .1. .1. .0. .1. .1. .0. .1. .1. .1
..2. .1. .2. .1. .2. .1. .1. .0. .2. .1. .2. .2. .1. .0. .2. .0
..0. .2. .2. .0. .0. .0. .2. .2. .3. .2. .3. .1. .1. .2. .0. .2
..1. .3. .1. .2. .2. .2. .1. .3. .4. .3. .3. .2. .2. .0. .3. .3
..2. .4. .0. .1. .1. .3. .3. .0. .5. .2. .4. .3. .0. .1. .2. .0
..2. .1. .3. .2. .3. .0. .4. .3. .2. .4. .2. .1. .2. .3. .2. .4
..3. .1. .1. .0. .1. .1. .2. .3. .6. .5. .4. .2. .1. .0. .4. .2

Crossrefs

Cf. A268956.

Sequence in context: A326513 A268953 A268954 * A268010 A215073 A215074

Adjacent sequences: A268952 A268953 A268954 * A268956 A268957 A268958

Keyword

nonn

Author

R. H. Hardin, Feb 16 2016

Status

approved