This site is supported by donations to The OEIS Foundation.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A099838 Expansion of (1-x)^2(1+x)/(1+x+x^2). 6
 1, -2, 0, 3, -3, 0, 3, -3, 0, 3, -3, 0, 3, -3, 0, 3, -3, 0, 3, -3, 0, 3, -3, 0, 3, -3, 0, 3, -3, 0, 3, -3, 0, 3, -3, 0, 3, -3, 0, 3, -3, 0, 3, -3, 0, 3, -3, 0, 3, -3, 0, 3, -3, 0, 3, -3, 0, 3, -3, 0, 3, -3, 0, 3, -3, 0, 3, -3, 0, 3, -3, 0, 3, -3, 0, 3, -3, 0, 3, -3, 0, 3, -3, 0, 3, -3, 0, 3, -3, 0, 3, -3, 0, 3, -3, 0, 3, -3, 0, 3, -3, 0 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,2 COMMENTS Partial sums are A099837. LINKS Index entries for linear recurrences with constant coefficients, signature (-1,-1). FORMULA a(n)=sum{k=0..n, (cos(2*pi*(n-k)/3)+sin(2*pi*(n-k)/3)/sqrt(3))C(2, k)(-1)^k} for n>=2 : a(n)=2*sqrt(3)*cos((4*n+1)*Pi/6) [From Richard Choulet, Apr 23 2009] CROSSREFS Sequence in context: A258817 A004557 A088276 * A127449 A138057 A053727 Adjacent sequences:  A099835 A099836 A099837 * A099839 A099840 A099841 KEYWORD easy,sign AUTHOR Paul Barry, Oct 27 2004 STATUS approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

Last modified July 17 02:52 EDT 2019. Contains 325092 sequences. (Running on oeis4.)