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A269468 Number of length-4 0..n arrays with no repeated value equal to the previous repeated value. 1
10, 66, 228, 580, 1230, 2310, 3976, 6408, 9810, 14410, 20460, 28236, 38038, 50190, 65040, 82960, 104346, 129618, 159220, 193620, 233310, 278806, 330648, 389400, 455650, 530010, 613116, 705628, 808230, 921630, 1046560, 1183776, 1334058 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

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

FORMULA

Empirical: a(n) = n^4 + 4*n^3 + 4*n^2 + n.

Conjectures from Colin Barker, Jan 23 2019: (Start)

G.f.: 2*x*(5 + 8*x - x^2) / (1 - x)^5.

a(n) = 5*a(n-1) - 10*a(n-2) + 10*a(n-3) - 5*a(n-4) + a(n-5) for n>5.

(End)

EXAMPLE

Some solutions for n=3:

..0. .3. .1. .2. .1. .1. .2. .2. .3. .3. .2. .0. .0. .2. .1. .3

..1. .3. .1. .2. .3. .0. .3. .1. .2. .3. .3. .1. .1. .2. .2. .2

..2. .0. .2. .3. .2. .0. .1. .0. .1. .2. .1. .0. .3. .0. .0. .3

..2. .1. .2. .2. .2. .3. .0. .1. .2. .1. .2. .0. .1. .1. .3. .2

CROSSREFS

Row 4 of A269467.

Sequence in context: A159838 A269679 A211056 * A024391 A074362 A080421

Adjacent sequences:  A269465 A269466 A269467 * A269469 A269470 A269471

KEYWORD

nonn

AUTHOR

R. H. Hardin, Feb 27 2016

STATUS

approved

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Last modified September 25 22:56 EDT 2022. Contains 356986 sequences. (Running on oeis4.)