|
| |
|
|
A275260
|
|
Number of n X 2 0..2 arrays with no element equal to any value at offset (-2,-1) (-2,1) or (-1,-1) and new values introduced in order 0..2.
|
|
1
|
|
|
|
2, 9, 24, 64, 172, 476, 1320, 3672, 10220, 28472, 79376, 221320, 617160, 1720976, 4799104, 13382832, 37319536, 104069760, 290210016, 809282592, 2256773088, 6293258240, 17549436800, 48938515904, 136470379968, 380562509568
(list;
graph;
refs;
listen;
history;
text;
internal format)
|
|
|
|
OFFSET
|
1,1
|
|
|
LINKS
|
R. H. Hardin, Table of n, a(n) for n = 1..210
|
|
|
FORMULA
|
Empirical: a(n) = 4*a(n-1) - 2*a(n-2) - 6*a(n-3) + 6*a(n-4) + 4*a(n-5) - 16*a(n-6) + 12*a(n-7) + 8*a(n-8) - 8*a(n-9) for n>10.
Empirical g.f.: x*(2 + x - 8*x^2 - 2*x^3 + 6*x^4 - 2*x^5 - 4*x^6 + 16*x^7 - 8*x^9) / (1 - 4*x + 2*x^2 + 6*x^3 - 6*x^4 - 4*x^5 + 16*x^6 - 12*x^7 - 8*x^8 + 8*x^9). - Colin Barker, Feb 02 2019
|
|
|
EXAMPLE
|
Some solutions for n=4:
..0..0. .0..0. .0..0. .0..0. .0..1. .0..0. .0..1. .0..1. .0..1. .0..1
..1..1. .1..2. .0..1. .1..1. .0..2. .1..1. .0..1. .1..1. .2..1. .0..2
..1..2. .1..2. .1..2. .1..2. .0..1. .2..2. .0..1. .0..2. .0..1. .0..2
..2..2. .1..2. .0..2. .0..0. .0..1. .2..0. .0..2. .2..2. .0..1. .1..2
|
|
|
CROSSREFS
|
Column 2 of A275266.
Sequence in context: A274543 A079997 A351252 * A248436 A354016 A222667
Adjacent sequences: A275257 A275258 A275259 * A275261 A275262 A275263
|
|
|
KEYWORD
|
nonn
|
|
|
AUTHOR
|
R. H. Hardin, Jul 21 2016
|
|
|
STATUS
|
approved
|
| |
|
|
