|
| |
|
|
A221536
|
|
Number of 0..2 arrays of length n with each element differing from at least one neighbor by something other than 1, starting with 0.
|
|
1
|
|
|
|
0, 2, 4, 10, 22, 54, 134, 334, 822, 2014, 4934, 12110, 29750, 73086, 179494, 440750, 1082262, 2657630, 6526342, 16026766, 39356662, 96646974, 237332966, 582812014, 1431196758, 3514554142, 8630600774, 21193942094, 52045411766, 127806567678
(list;
graph;
refs;
listen;
history;
text;
internal format)
|
|
|
|
OFFSET
|
1,2
|
|
|
COMMENTS
|
Column 2 of A221542.
|
|
|
LINKS
|
R. H. Hardin, Table of n, a(n) for n = 1..210
|
|
|
FORMULA
|
Empirical: a(n) = 3*a(n-1) -2*a(n-2) +4*a(n-4).
Empirical g.f.: 2*x^2*(1 - x + x^2) / (1 - 3*x + 2*x^2 - 4*x^4). - Colin Barker, Oct 18 2017
|
|
|
EXAMPLE
|
Some solutions for n=6
..0....0....0....0....0....0....0....0....0....0....0....0....0....0....0....0
..2....2....2....2....2....2....0....0....2....0....0....0....2....0....2....0
..2....0....2....2....2....2....2....0....0....2....2....1....0....2....0....2
..0....2....0....2....2....2....0....0....0....0....2....1....0....0....2....1
..2....2....2....1....2....0....2....1....1....1....0....2....2....0....0....1
..0....0....2....1....0....0....0....1....1....1....0....2....0....0....2....1
|
|
|
CROSSREFS
|
Sequence in context: A164990 A348009 A121285 * A290277 A030234 A205490
Adjacent sequences: A221533 A221534 A221535 * A221537 A221538 A221539
|
|
|
KEYWORD
|
nonn
|
|
|
AUTHOR
|
R. H. Hardin, Jan 19 2013
|
|
|
STATUS
|
approved
|
| |
|
|
