login
The OEIS is supported by the many generous donors to the OEIS Foundation.

 

Logo
Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A235880 Number of (n+1) X (4+1) 0..2 arrays with the minimum plus the upper median equal to the lower median plus the maximum in every 2 X 2 subblock. 1
339, 537, 951, 1833, 3759, 8097, 18231, 42873, 105279, 269457, 715911, 1963113, 5520399, 15823617, 45995991, 135038553, 399217119, 1185854577, 3533970471, 10554725193, 31569803439, 94520666337, 283184511351, 848798559033 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,1
LINKS
FORMULA
Empirical: a(n) = 6*a(n-1) - 11*a(n-2) + 6*a(n-3).
Conjectures from Colin Barker, Oct 19 2018: (Start)
G.f.: 3*x*(113 - 499*x + 486*x^2) / ((1 - x)*(1 - 2*x)*(1 - 3*x)).
a(n) = 3*(50 + 15*2^(1+n) + 3^n).
(End)
EXAMPLE
Some solutions for n=5:
..1..0..0..1..1....0..0..0..1..0....2..1..1..1..2....1..0..0..0..0
..1..0..0..1..1....1..1..1..0..1....1..2..2..2..1....1..0..0..0..0
..1..0..0..1..1....1..1..1..0..1....2..1..1..1..2....0..1..1..1..1
..0..1..1..0..0....0..0..0..1..0....2..1..1..1..2....0..1..1..1..1
..0..1..1..0..0....0..0..0..1..0....1..2..2..2..1....1..0..0..0..0
..1..0..0..1..1....0..0..0..1..0....2..1..1..1..2....0..1..1..1..1
CROSSREFS
Column 4 of A235884.
Sequence in context: A035750 A186043 A107546 * A158000 A252447 A252441
KEYWORD
nonn
AUTHOR
R. H. Hardin, Jan 16 2014
STATUS
approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recents
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified July 24 20:30 EDT 2024. Contains 374585 sequences. (Running on oeis4.)