|
|
A087945
|
|
Expansion of (1-2x-x^2)/((1-2x)(1-4x+x^2)).
|
|
0
|
|
|
1, 4, 14, 50, 182, 670, 2482, 9226, 34358, 128078, 477698, 1782202, 6650086, 24816094, 92610194, 345616490, 1289839382, 4813708270, 17964928162, 67045873306, 250218302918, 933826814078, 3485087904818, 13006522708042
(list;
graph;
refs;
listen;
history;
text;
internal format)
|
|
|
OFFSET
|
0,2
|
|
COMMENTS
|
|
|
LINKS
|
|
|
FORMULA
|
a(0)=1, a(2)=4, a(2)=14, a(n)=6a(n-1)-9a(n-2)+2a(n-3), n>2; a(n)=(2^n+(1-sqrt(3))(2-sqrt(3))^n+(1+sqrt(3))(2+sqrt(3))^n)/3.
|
|
MATHEMATICA
|
CoefficientList[Series[(1-2x-x^2)/((1-2x)(1-4x+x^2)), {x, 0, 30}], x] (* or *) LinearRecurrence[{6, -9, 2}, {1, 4, 14}, 30] (* Harvey P. Dale, Aug 21 2021 *)
|
|
CROSSREFS
|
|
|
KEYWORD
|
easy,nonn
|
|
AUTHOR
|
|
|
STATUS
|
approved
|
|
|
|