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A217950 Number of n element 0..3 arrays with each element the minimum of 4 adjacent elements of a random 0..3 array of n+3 elements. 1
4, 16, 50, 130, 296, 624, 1289, 2741, 6134, 14269, 33577, 78304, 179671, 406765, 915275, 2061311, 4664237, 10605587, 24181837, 55152622, 125626530, 285683099, 648937238, 1473615534, 3347303199, 7607369029, 17296530794, 39333312344 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Column 4 of A217954.

LINKS

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

FORMULA

Empirical: a(n) = 4*a(n-1) - 6*a(n-2) + 4*a(n-3) - a(n-4) + 6*a(n-5) - 4*a(n-6) + 6*a(n-7) + 4*a(n-8) + 5*a(n-9) + a(n-10) + 3*a(n-11) + 2*a(n-12) + a(n-13).

Empirical g.f.: x*(1 - x + x^2)*(2 + 2*x + x^2)*(2 + 4*x^2 + 4*x^3 + 5*x^4 + 2*x^5 + 3*x^6 + 2*x^7 + x^8) / (1 - 4*x + 6*x^2 - 4*x^3 + x^4 - 6*x^5 + 4*x^6 - 6*x^7 - 4*x^8 - 5*x^9 - x^10 - 3*x^11 - 2*x^12 - x^13). - Colin Barker, Jul 23 2018

EXAMPLE

Some solutions for n=4:

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

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

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

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

CROSSREFS

Cf. A217954.

Sequence in context: A217953 A217952 A217951 * A217949 A227675 A203094

Adjacent sequences:  A217947 A217948 A217949 * A217951 A217952 A217953

KEYWORD

nonn

AUTHOR

R. H. Hardin, Oct 15 2012

STATUS

approved

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Last modified April 13 10:24 EDT 2021. Contains 342935 sequences. (Running on oeis4.)