The OEIS is supported by the many generous donors to the OEIS Foundation.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A132954 Period 6: repeat [1, 2, 4, -1, -2, -4]. 2
 1, 2, 4, -1, -2, -4, 1, 2, 4, -1, -2, -4, 1, 2, 4, -1, -2, -4, 1, 2, 4, -1, -2, -4, 1, 2, 4, -1, -2, -4, 1, 2, 4, -1, -2, -4, 1, 2, 4, -1, -2, -4, 1, 2, 4, -1, -2, -4, 1, 2, 4, -1, -2, -4, 1, 2, 4, -1, -2, -4, 1, 2, 4, -1, -2, -4, 1, 2, 4, -1, -2, -4, 1, 2 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,2 COMMENTS Nonsimple continued fraction expansion of (5+sqrt(13))/6 = 1.434258545... - R. J. Mathar, Mar 08 2012 LINKS Table of n, a(n) for n=0..73. Index entries for linear recurrences with constant coefficients, signature (0,0,-1). FORMULA a(n) = -a(n-3) for n>2. G.f.: (1+2*x+4*x^2)/((1+x)*(x^2-x+1)). [R. J. Mathar, Apr 13 2010] a(n) = cos(n*Pi) + 2*sqrt(3)*sin(n*Pi/3). - Wesley Ivan Hurt, Jun 20 2016 MAPLE A132954:=n->[1, 2, 4, -1, -2, -4][(n mod 6)+1]: seq(A132954(n), n=0..100); # Wesley Ivan Hurt, Jun 20 2016 MATHEMATICA PadRight[{}, 100, {1, 2, 4, -1, -2, -4}] (* Wesley Ivan Hurt, Jun 20 2016 *) PROG (PARI) a(n)=(2^n%7)*(-1)^(n%6>2) \\ Jaume Oliver Lafont, Mar 24 2009 (Magma) &cat [[1, 2, 4, -1, -2, -4]^^20]; // Wesley Ivan Hurt, Jun 20 2016 CROSSREFS Sequence in context: A206475 A227184 A124911 * A069705 A375030 A106645 Adjacent sequences: A132951 A132952 A132953 * A132955 A132956 A132957 KEYWORD sign,easy AUTHOR Paul Curtz, Nov 19 2007 STATUS approved

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

Last modified August 11 13:51 EDT 2024. Contains 375069 sequences. (Running on oeis4.)