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A269405 Number of length-n 0..4 arrays with no repeated value greater than or equal to the previous repeated value. 1
5, 25, 120, 570, 2670, 12380, 56890, 259445, 1175355, 5293671, 23718780, 105781845, 469798125, 2078552055, 9164402118, 40277785365, 176503698495, 771372344695, 3362640467600, 14624384170213, 63463229049585, 274836205944615 (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) = 20*a(n-1) - 150*a(n-2) + 460*a(n-3) - 65*a(n-4) - 2472*a(n-5) + 2320*a(n-6) + 6400*a(n-7) - 3840*a(n-8) - 10240*a(n-9) - 4096*a(n-10).

Empirical g.f.: x*(5 - 75*x + 370*x^2 - 380*x^3 - 1905*x^4 + 3265*x^5 + 5590*x^6 - 5865*x^7 - 11455*x^8 - 4339*x^9) / ((1 + x)^4*(1 - 4*x)^6). - Colin Barker, Jan 21 2019

EXAMPLE

Some solutions for n=7:

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

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

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

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

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

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

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

CROSSREFS

Column 4 of A269409

Sequence in context: A268940 A269636 A269533 * A269674 A269602 A089927

Adjacent sequences:  A269402 A269403 A269404 * A269406 A269407 A269408

KEYWORD

nonn

AUTHOR

R. H. Hardin, Feb 25 2016

STATUS

approved

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Last modified June 1 19:32 EDT 2020. Contains 334762 sequences. (Running on oeis4.)