|
| |
|
|
A069440
|
|
Half the number of n X 2 binary arrays with no path of adjacent 1's or adjacent 0's from top row to bottom row.
|
|
0
|
|
|
|
0, 2, 16, 88, 414, 1810, 7616, 31376, 127710, 516170, 2077552, 8341288, 33440190, 133941922, 536205056, 2145876128, 8586053694, 34350369050, 137416333936, 549701205496, 2198891419230, 8795774741170, 35183603690432, 140735633277488, 562945474867230
(list;
graph;
refs;
listen;
history;
text;
internal format)
|
|
|
|
OFFSET
|
1,2
|
|
|
LINKS
|
|
|
|
FORMULA
|
a(n) = 7*a(n-1) - 13*a(n-2) + 3*a(n-3) + 4*a(n-4).
G.f.: 2*x^2*(1+x+x^2)/((1-x)*(1-4*x)*(1-2*x-x^2)). (End)
|
|
|
CROSSREFS
|
|
|
|
KEYWORD
|
nonn,easy,changed
|
|
|
AUTHOR
|
|
|
|
EXTENSIONS
|
|
|
|
STATUS
|
approved
|
| |
|
|
