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 A097512 a(n) = 6*Lucas(2n) - Fib(2n+2). 1
 11, 15, 34, 87, 227, 594, 1555, 4071, 10658, 27903, 73051, 191250, 500699, 1310847, 3431842, 8984679, 23522195, 61581906, 161223523, 422088663, 1105042466, 2893038735, 7574073739, 19829182482, 51913473707, 135911238639 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,1 COMMENTS Sequence relates bisections of Lucas and Fibonacci numbers. LINKS Vincenzo Librandi, Table of n, a(n) for n = 0..200 Tanya Khovanova, Recursive Sequences Index entries for linear recurrences with constant coefficients, signature (3,-1). FORMULA a(n) = 8*Lucas(2n) - Lucas(2n+2) - 2*Fib(2n-1) = 8*A005248(n) - A005248(n+1) - 2*A001519(n). a(n+1)/a(n) approaches the golden ratio phi + 1 = (3+sqrt(5))/2. a(n) = 3*a(n-1)-a(n-2) with a(0)=11 and a(1)=15. G.f.: (11-18x)/(1-3x+x^2). [Philippe Deléham, Nov 16 2008] a(n) = (11/2)*[(3/2)+(1/2)*sqrt(5)]^n-(3/10)*[(3/2)+(1/2)*sqrt4(5)]^n*sqrt(5)+(3/10)*[(3/2)-(1/2) *sqrt(5]^n*sqrt(5)+(11/2)*[(3/2)-(1/2)*sqrt(5)]^n, with n>=0. [Paolo P. Lava, Nov 19 2008] a(n) = 4*Fibonacci(2n+1) + 7*Fibonacci(2n-1) = 4*Lucas(2n) + 3*Fibonacci(2n-1). [Ron Knott, Jul 01 2013] MATHEMATICA Table[6LucasL[2n]-Fibonacci[2n+2], {n, 0, 30}] (* or *) LinearRecurrence[ {3, -1}, {11, 15}, 30] (* Harvey P. Dale, Oct 02 2011 *) PROG (MAGMA) [8*Lucas(2*n) - Lucas(2*n+2) - 2*Fibonacci(2*n-1): n in [0..30]]; // Vincenzo Librandi, Oct 03 2011 CROSSREFS Cf. A005248, A005248, A022133. Sequence in context: A275242 A030099 A085597 * A032490 A068483 A241679 Adjacent sequences:  A097509 A097510 A097511 * A097513 A097514 A097515 KEYWORD nonn,easy AUTHOR Creighton Dement, Aug 26 2004 EXTENSIONS New definition from Ralf Stephan, Dec 01 2004 STATUS approved

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Last modified November 19 08:51 EST 2017. Contains 294923 sequences.