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!)
A204699 Number of n X 2 0..2 arrays with no occurrence of three equal elements in a row horizontally, vertically or nw-to-se diagonally, and new values 0..2 introduced in row major order. 3
2, 14, 96, 726, 5400, 40344, 301056, 2247264, 16773504, 125199744, 934502400, 6975223296, 52063770624, 388609284096, 2900619165696, 21650516238336, 161601653145600, 1206211160408064, 9003282670288896, 67201416721465344 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,1
COMMENTS
Column 2 of A204705.
LINKS
FORMULA
Empirical: a(n) = 6*a(n-1) + 12*a(n-2) - 8*a(n-3) for n>5.
Empirical g.f.: 2*x*(1 - 2*x)*(1 + 3*x - x^3) / ((1 + 2*x)*(1 - 8*x + 4*x^2)). - Colin Barker, Feb 23 2018
EXAMPLE
Some solutions for n=5:
..0..0....0..0....0..1....0..1....0..1....0..1....0..0....0..1....0..0....0..1
..0..1....0..1....1..1....2..0....2..0....0..2....0..1....0..2....1..2....0..0
..2..0....2..1....0..2....0..1....1..2....2..0....2..0....1..1....0..2....2..0
..1..2....2..2....2..2....2..2....2..0....0..2....1..0....1..2....1..0....0..2
..0..2....0..0....1..0....2..1....0..1....1..0....0..2....2..1....2..1....0..0
CROSSREFS
Cf. A204705.
Sequence in context: A164891 A141146 A267913 * A286445 A322262 A109808
KEYWORD
nonn
AUTHOR
R. H. Hardin, Jan 18 2012
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 February 28 02:21 EST 2024. Contains 370379 sequences. (Running on oeis4.)