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A245159 Number of length n 0..4 arrays with new values introduced in order from both ends. 1
1, 1, 2, 4, 9, 23, 65, 199, 654, 2296, 8568, 33794, 140039, 605869, 2718531, 12564289, 59419764, 285878342, 1392536354, 6842206084, 33819153429, 167827213315, 835048228437, 4162123757579, 20768689294634, 103709892420388 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,3

LINKS

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

FORMULA

Empirical: a(n) = 17*a(n-1) - 118*a(n-2) + 434*a(n-3) - 913*a(n-4) + 1097*a(n-5) - 696*a(n-6) + 180*a(n-7) for n>8.

Conjectures from Colin Barker, Nov 03 2018: (Start)

G.f.: x*(1 - 16*x + 103*x^2 - 346*x^3 + 656*x^4 - 710*x^5 + 425*x^6 - 124*x^7) / ((1 - x)^2*(1 - 2*x)^2*(1 - 3*x)^2*(1 - 5*x)).

a(n) = (-3375 - 525*2^(4+n) - 1300*3^n + 3*5^n + 100*(297+9*2^(2+n) + 2*3^n)*n) / 43200.

(End)

EXAMPLE

Some solutions for n=7:

..0....0....0....0....0....0....0....0....0....0....0....0....0....0....0....0

..0....1....0....1....0....1....0....1....1....0....1....1....0....1....0....0

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

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

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

..0....1....0....1....1....0....1....1....1....1....1....0....1....1....1....1

..0....0....0....0....0....0....0....0....0....0....0....0....0....0....0....0

CROSSREFS

Column 4 of A245163.

Sequence in context: A164039 A014137 A245158 * A245160 A245161 A245162

Adjacent sequences:  A245156 A245157 A245158 * A245160 A245161 A245162

KEYWORD

nonn

AUTHOR

R. H. Hardin, Jul 12 2014

STATUS

approved

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Last modified January 20 12:47 EST 2019. Contains 319330 sequences. (Running on oeis4.)