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!)
A183624 Number of (n+1) X 2 0..2 arrays with every 2 x 2 subblock summing to 4. 3
19, 45, 115, 309, 859, 2445, 7075, 20709, 61099, 181245, 539635, 1610709, 4815739, 14414445, 43177795, 129402309, 387944779, 1163310045, 3488881555, 10464547509, 31389448219, 94159956045, 282463090915, 847355718309, 2542000046059 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,1
COMMENTS
Column 1 of A183632.
LINKS
FORMULA
Empirical: a(n) = 6*a(n-1) - 11*a(n-2) + 6*a(n-3).
Conjectures from Colin Barker, Feb 22 2018: (Start)
G.f.: x*(19 - 69*x + 54*x^2) / ((1 - x)*(1 - 2*x)*(1 - 3*x)).
a(n) = 2 + 2^(2+n) + 3^(1+n).
(End)
EXAMPLE
Some solutions for 3 X 2:
..2..0....2..0....1..2....2..0....1..0....0..2....2..1....0..2....2..0....0..2
..2..0....1..1....1..0....0..2....1..2....0..2....0..1....1..1....2..0....2..0
..2..0....2..0....2..1....1..1....0..1....1..1....1..2....1..1....1..1....0..2
CROSSREFS
Cf. A183632.
Sequence in context: A183632 A359558 A245864 * A115249 A325451 A135029
KEYWORD
nonn
AUTHOR
R. H. Hardin, Jan 06 2011
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 March 29 06:34 EDT 2024. Contains 371265 sequences. (Running on oeis4.)