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 A081079 Lucas(4n+2)-3, or 5*Fibonacci(2n)*Fibonacci(2n+2). 0
 0, 15, 120, 840, 5775, 39600, 271440, 1860495, 12752040, 87403800, 599074575, 4106118240, 28143753120, 192900153615, 1322157322200, 9062201101800, 62113250390415, 425730551631120, 2918000611027440, 20000273725560975 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,2 REFERENCES Hugh C. Williams, Edouard Lucas and Primality Testing, John Wiley and Sons, 1998, p. 75 LINKS Index to sequences with linear recurrences with constant coefficients, signature (8,-8,1). [From R. J. Mathar, Sep 03 2010] FORMULA a(n) = 8a(n-1)-8a(n-2)+a(n-3) a(n)=-3+(3/2)*{[(7/2)-(3/2)*sqrt(5)]^n+[(7/2)+(3/2)*sqrt(5)]^n}+(1/2)*sqrt(5)*{[(7/2)+(3/2)*sqrt(5)]^n -[(7/2)-(3/2)*sqrt(5)]^n}, with n>=0 [From Paolo P. Lava, Dec 01 2008] G.f.: -15*x/(x-1)/(x^2-7*x+1). a(n) = 15*A092521(n) = 5*A058038(n). [From R. J. Mathar, Sep 03 2010] MAPLE luc := proc(n) option remember: if n=0 then RETURN(2) fi: if n=1 then RETURN(1) fi: luc(n-1)+luc(n-2): end: for n from 0 to 40 do printf(`%d, `, luc(4*n+2)-3) od: CROSSREFS Cf. A000032 (Lucas numbers), A000045 (Fibonacci numbers). Sequence in context: A162635 A010967 A022580 * A138424 A120794 A038743 Adjacent sequences:  A081076 A081077 A081078 * A081080 A081081 A081082 KEYWORD nonn,easy AUTHOR R. K. Guy, Mar 04, 2003 EXTENSIONS More terms and Maple code from James A. Sellers, Mar 05, 2003 STATUS approved

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