

A202730


Number of n X 3 nonnegative integer arrays each row and column an ascent sequence (interior element no greater than one plus upsteps 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
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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(n1) 10*a(n2) 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: A277556 A321179 A166114 * A292080 A291376 A273319
Adjacent sequences: A202727 A202728 A202729 * A202731 A202732 A202733


KEYWORD

nonn


AUTHOR

R. H. Hardin, Dec 23 2011


STATUS

approved



