|
| |
|
|
A183980
|
|
1/4 the number of (n+1) X 4 binary arrays with all 2 X 2 subblock sums the same.
|
|
1
|
|
|
|
9, 11, 14, 20, 30, 50, 86, 158, 294, 566, 1094, 2150, 4230, 8390, 16646, 33158, 66054, 131846, 263174, 525830, 1050630, 2100230, 4198406, 8394758, 16785414, 33566726, 67125254, 134242310, 268468230, 536920070, 1073807366, 2147581958, 4295098374
(list;
graph;
refs;
listen;
history;
text;
internal format)
|
|
|
|
OFFSET
|
1,1
|
|
|
COMMENTS
|
Column 3 of A183986.
|
|
|
LINKS
|
R. H. Hardin, Table of n, a(n) for n = 1..200
|
|
|
FORMULA
|
Empirical: a(n)=3*a(n-1)-6*a(n-3)+4*a(n-4).
Conjectures from Colin Barker, Apr 07 2018: (Start)
G.f.: x*(9 - 16*x - 19*x^2 + 32*x^3) / ((1 - x)*(1 - 2*x)*(1 - 2*x^2)).
a(n) = (3*2^(n/2) + 2^n + 12) / 2 for n even.
a(n) = 2^((n-5)/2+3) + 2^(n-1) + 6 for n odd.
(End)
|
|
|
EXAMPLE
|
Some solutions for 5 X 4.
..0..1..0..1....1..1..1..1....0..0..1..1....1..0..1..0....1..1..1..0
..1..1..1..1....0..0..0..0....1..1..0..0....1..1..1..1....0..0..0..1
..1..0..1..0....1..1..1..1....0..0..1..1....1..0..1..0....1..1..1..0
..1..1..1..1....0..0..0..0....1..1..0..0....1..1..1..1....0..0..0..1
..0..1..0..1....1..1..1..1....0..0..1..1....0..1..0..1....1..1..1..0
|
|
|
CROSSREFS
|
Cf. A183986.
Sequence in context: A307188 A209321 A212816 * A101754 A348614 A113339
Adjacent sequences: A183977 A183978 A183979 * A183981 A183982 A183983
|
|
|
KEYWORD
|
nonn
|
|
|
AUTHOR
|
R. H. Hardin, Jan 08 2011
|
|
|
STATUS
|
approved
|
| |
|
|
