|
|
A130778
|
|
Period 6: repeat [1, -1, -3, -3, -1, 1].
|
|
1
|
|
|
1, -1, -3, -3, -1, 1, 1, -1, -3, -3, -1, 1, 1, -1, -3, -3, -1, 1, 1, -1, -3, -3, -1, 1, 1, -1, -3, -3, -1, 1, 1, -1, -3, -3, -1, 1, 1, -1, -3, -3, -1, 1, 1, -1, -3, -3, -1, 1, 1, -1, -3, -3, -1, 1, 1, -1, -3, -3, -1, 1, 1, -1, -3, -3, -1, 1, 1, -1, -3, -3
(list;
graph;
refs;
listen;
history;
text;
internal format)
|
|
|
OFFSET
|
0,3
|
|
COMMENTS
|
With offset 1, a(n) satisfies the interesting recurrence: a(n+1) = Sum_{k=1..n} binomial(n, k)*(-1)^k*a(k); see Mathematica code below. - John M. Campbell, May 05 2012
|
|
LINKS
|
|
|
FORMULA
|
G.f.: (1-3*x+x^2)/(1-2*x+2*x^2-x^3).
a(n) = 2*a(n-1) - 2*a(n-2) + a(n-3) for n>2.
a(n) = (6*cos(n*Pi/3) - 2*sqrt(3)*sin(n*Pi/3) - 3)/3. (End)
|
|
MAPLE
|
|
|
MATHEMATICA
|
Table1 = {1}; a[1] = 1; n = 1; While[n < 314, a[n + 1] = Sum[Binomial[n, k]*(-1)^k*a[k], {k, 1, n}]; AppendTo[Table1, a[n + 1]]; n++]; Print[Table1] (* John M. Campbell, May 05 2012 *)
|
|
PROG
|
|
|
CROSSREFS
|
|
|
KEYWORD
|
sign,easy
|
|
AUTHOR
|
|
|
STATUS
|
approved
|
|
|
|