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A235888 Number of (n+1) X (3+1) 0..3 arrays with the minimum plus the upper median equal to the lower median plus the maximum in every 2 X 2 subblock. 1
352, 568, 1096, 2536, 6952, 21928, 76456, 283816, 1091752, 4280488, 16949416, 67453096, 269123752, 1075118248, 4297719976, 17185374376, 68730486952, 274899927208, 1099555668136, 4398134591656, 17592362205352, 70369096499368 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,1
LINKS
FORMULA
Empirical: a(n) = 7*a(n-1) - 14*a(n-2) + 8*a(n-3).
Conjectures from Colin Barker, Oct 19 2018: (Start)
G.f.: 8*x*(44 - 237*x + 256*x^2) / ((1 - x)*(1 - 2*x)*(1 - 4*x)).
a(n) = 4*(42 + 21*2^n + 4^n).
(End)
EXAMPLE
Some solutions for n=4:
..3..1..3..3....1..3..1..3....3..3..1..3....2..2..2..2....2..3..0..2
..1..3..1..1....1..3..1..3....3..3..1..3....0..0..0..0....2..3..0..2
..1..3..1..1....1..3..1..3....1..1..3..1....1..1..1..1....2..3..0..2
..3..1..3..3....1..3..1..3....1..1..3..1....1..1..1..1....2..3..0..2
..3..1..3..3....3..1..3..1....3..3..1..3....1..1..1..1....2..3..0..2
CROSSREFS
Column 3 of A235893.
Sequence in context: A167820 A145633 A252250 * A256025 A256771 A256764
KEYWORD
nonn
AUTHOR
R. H. Hardin, Jan 16 2014
STATUS
approved

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Last modified June 24 01:53 EDT 2024. Contains 373661 sequences. (Running on oeis4.)