|
|
A038990
|
|
Expansion of (1-x-x^2+2*x^3) / ((1-x)*(1+x)*(1-3*x+x^2)).
|
|
1
|
|
|
1, 2, 5, 14, 37, 98, 257, 674, 1765, 4622, 12101, 31682, 82945, 217154, 568517, 1488398, 3896677, 10201634, 26708225, 69923042, 183060901, 479259662, 1254718085, 3284894594, 8599965697, 22515002498, 58945041797, 154320122894, 404015326885, 1057725857762
(list;
graph;
refs;
listen;
history;
text;
internal format)
|
|
|
OFFSET
|
0,2
|
|
LINKS
|
|
|
FORMULA
|
a(0)=1, a(1)=2, a(2)=5, a(3)=14, a(n)=3*a(n-1)-3*a(n-3)+a(n-4). - Harvey P. Dale, Feb 17 2012
a(n) = (-1)*(2^(-1-n)*((-2)^n + 5*2^n - 8*(3-sqrt(5))^n - 8*(3+sqrt(5))^n)) / 5. - Colin Barker, Jul 16 2017
|
|
MAPLE
|
A001906 := proc(n) combinat[fibonacci](2*n) ; end proc:
|
|
MATHEMATICA
|
CoefficientList[Series[(1-x-x^2+2x^3)/((1-x)(1+x)(1-3x+x^2)), {x, 0, 30}], x] (* or *) LinearRecurrence[{3, 0, -3, 1}, {1, 2, 5, 14}, 30] (* Harvey P. Dale, Feb 17 2012 *)
|
|
PROG
|
|
|
CROSSREFS
|
|
|
KEYWORD
|
nonn,easy
|
|
AUTHOR
|
|
|
STATUS
|
approved
|
|
|
|