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A269290 Number of 2 X n 0..3 arrays with some element plus some horizontally or antidiagonally adjacent neighbor totalling three no more than once. 1
16, 216, 2124, 19188, 164556, 1363572, 11026764, 87559668, 685523916, 5306911092, 40706083404, 309846524148, 2343253251276, 17623065834612, 131903512372044, 983118947312628, 7300393156146636, 54032675767734132, 398738196097092684 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,1
LINKS
FORMULA
Empirical: a(n) = 14*a(n-1) - 49*a(n-2) for n>4.
Conjectures from Colin Barker, Jan 21 2019: (Start)
G.f.: 4*x*(4 - 2*x - 29*x^2 + 9*x^3) / (1 - 7*x)^2.
a(n) = 36 * 7^(n-4) * (120*n+53) for n>2.
(End)
EXAMPLE
Some solutions for n=4:
..0..0..2..1. .1..0..1..3. .1..3..2..2. .2..0..2..2. .3..1..3..2
..2..2..3..3. .1..1..2..2. .3..2..2..0. .1..0..3..1. .0..3..2..0
CROSSREFS
Row 2 of A269289.
Sequence in context: A125473 A245828 A239096 * A297098 A159739 A181247
KEYWORD
nonn
AUTHOR
R. H. Hardin, Feb 21 2016
STATUS
approved

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Last modified February 28 07:05 EST 2024. Contains 370387 sequences. (Running on oeis4.)