|
|
A220407
|
|
Equals two maps: number of 2 X n binary arrays indicating the locations of corresponding elements equal to exactly two of their horizontal, diagonal and antidiagonal neighbors in a random 0..1 2 X n array.
|
|
1
|
|
|
1, 6, 17, 40, 93, 206, 431, 924, 1863, 3898, 7773, 15992, 31825, 64758, 128963, 260596, 519603, 1045490, 2086817, 4188144, 8365965, 16764910, 33505143, 67084268, 134111071, 268386282, 536641349, 1073643496, 2146991913, 4294770662
(list;
graph;
refs;
listen;
history;
text;
internal format)
|
|
|
OFFSET
|
1,2
|
|
COMMENTS
|
|
|
LINKS
|
|
|
FORMULA
|
Empirical: a(n) = 2*a(n-1) + 7*a(n-2) - 14*a(n-3) - 19*a(n-4) + 38*a(n-5) + 25*a(n-6) - 50*a(n-7) - 16*a(n-8) + 32*a(n-9) + 4*a(n-10) - 8*a(n-11).
Empirical g.f.: x*(1 + 4*x - 2*x^2 - 22*x^3 - 3*x^4 + 54*x^5 - 2*x^6 - 64*x^7 + 20*x^8 + 32*x^9 - 16*x^10) / ((1 - x)^3*(1 + x)^3*(1 - 2*x)*(1 - 2*x^2)^2). - Colin Barker, Jul 31 2018
|
|
EXAMPLE
|
Some solutions for n=3:
..1..1..1....0..1..1....0..0..1....0..0..0....0..1..1....0..0..1....1..0..1
..0..1..0....1..1..0....0..0..0....0..0..0....0..1..1....1..0..1....0..0..1
|
|
CROSSREFS
|
|
|
KEYWORD
|
nonn
|
|
AUTHOR
|
|
|
STATUS
|
approved
|
|
|
|