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A202730 Number of n X 3 nonnegative integer arrays each row and column an ascent sequence (interior element no greater than one plus up-steps preceding it) and the lower right element equal to min(n,3)-1. 1
1, 2, 2, 14, 78, 406, 2062, 10374, 51998, 260246, 1301742, 6509734, 32550718, 162757686, 813796622, 4068999494, 20345030238, 101725216726, 508626214702, 2543131335654, 12715657202558, 63578287061366, 317891437403982 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

Column 3 of A202735.

LINKS

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

FORMULA

Empirical: a(n) = 7*a(n-1) -10*a(n-2) for n>4.

Conjectures from Colin Barker, Jun 01 2018: (Start)

G.f.: x*(1 - 5*x - 2*x^2 + 20*x^3) / ((1 - 2*x)*(1 - 5*x)).

a(n) = (4*5^n - 25*2^n)/150 for n>2.

(End)

EXAMPLE

Some solutions for n=4:

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

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

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

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

CROSSREFS

Cf. A202735.

Sequence in context: A194689 A277556 A166114 * A292080 A291376 A273319

Adjacent sequences:  A202727 A202728 A202729 * A202731 A202732 A202733

KEYWORD

nonn

AUTHOR

R. H. Hardin, Dec 23 2011

STATUS

approved

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Last modified June 18 20:00 EDT 2018. Contains 305571 sequences. (Running on oeis4.)