|
| |
|
|
A052904
|
|
Expansion of (1-x)/(1-2x-4x^2+4x^3).
|
|
1
|
|
|
|
1, 1, 6, 12, 44, 112, 352, 976, 2912, 8320, 24384, 70400, 205056, 594176, 1726976, 5010432, 14552064, 42237952, 122642432, 356028416, 1033674752, 3000893440, 8712372224, 25293619200, 73433153536, 213191294976, 618940727296
(list;
graph;
refs;
listen;
history;
text;
internal format)
|
|
|
|
OFFSET
|
0,3
|
|
|
LINKS
|
|
|
|
FORMULA
|
G.f.: -(-1+x)/(1-2*x-4*x^2+4*x^3)
Recurrence: {a(1)=1, a(0)=1, a(2)=6, 4*a(n)-4*a(n+1)-2*a(n+2)+a(n+3)=0}
Sum(-1/37*(-4-14*_alpha+13*_alpha^2)*_alpha^(-1-n), _alpha=RootOf(1-2*_Z-4*_Z^2+4*_Z^3))
|
|
|
MAPLE
|
spec := [S, {S=Sequence(Prod(Z, Union(Sequence(Z), Z, Z, Z, Z)))}, unlabeled]: seq(combstruct[count](spec, size=n), n=0..20);
|
|
|
MATHEMATICA
|
CoefficientList[Series[(1-x)/(1-2x-4x^2+4x^3), {x, 0, 30}], x] (* or *) LinearRecurrence[{2, 4, -4}, {1, 1, 6}, 30] (* Harvey P. Dale, Jan 17 2013 *)
|
|
|
CROSSREFS
|
|
|
|
KEYWORD
|
easy,nonn
|
|
|
AUTHOR
|
encyclopedia(AT)pommard.inria.fr, Jan 25 2000
|
|
|
EXTENSIONS
|
|
|
|
STATUS
|
approved
|
| |
|
|
