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A269636 Number of length-n 0..4 arrays with no repeated value differing from the previous repeated value by other than plus two or minus 1. 1
5, 25, 120, 567, 2637, 12125, 55225, 249600, 1120868, 5006144, 22255415, 98544130, 434827380, 1912861067, 8392454605, 36733957588, 160447861687, 699496998228, 3044446874255, 13230474539089, 57418454111103, 248881927670961 (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) = 13*a(n-1) - 51*a(n-2) + 15*a(n-3) + 240*a(n-4) - 96*a(n-5) - 509*a(n-6) - 268*a(n-7).

Empirical g.f.: x*(5 - 40*x + 50*x^2 + 207*x^3 - 189*x^4 - 559*x^5 - 273*x^6) / ((1 - 4*x)*(1 - 9*x + 15*x^2 + 45*x^3 - 60*x^4 - 144*x^5 - 67*x^6)). - Colin Barker, Jan 25 2019

EXAMPLE

Some solutions for n=7:

..2. .0. .3. .0. .3. .2. .4. .3. .3. .3. .3. .3. .0. .0. .3. .0

..1. .3. .2. .4. .0. .1. .0. .1. .4. .0. .2. .1. .0. .1. .0. .4

..4. .4. .3. .2. .2. .1. .3. .0. .0. .1. .4. .4. .2. .3. .3. .0

..1. .1. .4. .2. .4. .3. .0. .4. .4. .2. .0. .4. .0. .4. .4. .4

..1. .2. .4. .4. .0. .2. .4. .0. .1. .1. .1. .2. .3. .3. .1. .4

..3. .3. .2. .2. .1. .4. .2. .0. .4. .0. .1. .3. .1. .3. .4. .2

..3. .2. .1. .4. .0. .1. .2. .3. .4. .0. .4. .3. .2. .1. .3. .4

CROSSREFS

Column 4 of A269640.

Sequence in context: A110212 A344097 A268940 * A269533 A269405 A269674

Adjacent sequences:  A269633 A269634 A269635 * A269637 A269638 A269639

KEYWORD

nonn

AUTHOR

R. H. Hardin, Mar 02 2016

STATUS

approved

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Last modified September 25 05:14 EDT 2021. Contains 347652 sequences. (Running on oeis4.)