A268954 Number of length-n 0..6 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, 3073, 15579, 84572, 485726, 2918103, 18146537, 115772922, 752410412, 4954432229, 32923518967, 220172576536, 1478770322954, 9961340359315, 67235635905765, 454423768826774, 3074025717951560

Offset

1,2

Comments

Column 6 of A268956.

Links

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

Formula

Empirical: a(n) = 27*a(n-1) -280*a(n-2) +1258*a(n-3) -781*a(n-4) -13833*a(n-5) +39878*a(n-6) +32104*a(n-7) -261136*a(n-8) +111564*a(n-9) +754544*a(n-10) -663920*a(n-11) -1052352*a(n-12) +1135872*a(n-13) +580608*a(n-14) -663552*a(n-15) for n>17

Example

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

Crossrefs

Cf. A268956.

Sequence in context: A215072 A326513 A268953 * A268955 A268010 A215073

Adjacent sequences: A268951 A268952 A268953 * A268955 A268956 A268957

Keyword

nonn

Author

R. H. Hardin, Feb 16 2016

Status

approved