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 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 (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 Index entries for sequences related to linear recurrences with constant coefficients, signature (0,0,-1). FORMULA a(n)=(1/6)*{-5*(n mod 6)+2*[(n+1) mod 6]+[(n+2) mod 6]+5*[(n+3) mod 6]-2*[(n+4) mod 6]-[(n+5) mod 6]} - Paolo P. Lava, Nov 30 2007 a(n) = -a(n-3). G.f.: (1+2*x+4*x^2)/((1+x) * (x^2-x+1)). [From R. J. Mathar, Apr 13 2010] PROG (PARI) a(n)=(2^n%7)*(-1)^(n%6>2) [From Jaume Oliver Lafont, Mar 24 2009] CROSSREFS Sequence in context: A215905 A206475 A124911 * A069705 A106645 A115314 Adjacent sequences:  A132951 A132952 A132953 * A132955 A132956 A132957 KEYWORD sign,easy AUTHOR Paul Curtz, Nov 19 2007 STATUS approved

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