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 A001588 a(n) = a(n-1) + a(n-2) - 1. (Formerly M2279 N0901) 4
 1, 3, 3, 5, 7, 11, 17, 27, 43, 69, 111, 179, 289, 467, 755, 1221, 1975, 3195, 5169, 8363, 13531, 21893, 35423, 57315, 92737, 150051, 242787, 392837, 635623, 1028459, 1664081, 2692539, 4356619, 7049157, 11405775, 18454931, 29860705, 48315635 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,2 REFERENCES N. J. A. Sloane, A Handbook of Integer Sequences, Academic Press, 1973 (includes this sequence). N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence). LINKS T. D. Noe, Table of n, a(n) for n = 0..500 Martin Griffiths, On a Matrix Arising from a Family of Iterated Self-Compositions, Journal of Integer Sequences, 18 (2015), #15.11.8. J. A. H. Hunter and F. D. Parker, Problem B-100, Fib. Quart., 5 (1967), p. 288. Simon Plouffe, Approximations de séries génératrices et quelques conjectures, Dissertation, Université du Québec à Montréal, 1992. Simon Plouffe, 1031 Generating Functions and Conjectures, Université du Québec à Montréal, 1992. Index entries for linear recurrences with constant coefficients, signature (2,0,-1). FORMULA From Henry Bottomley, Feb 20 2001: (Start) a(n) = 2*Fibonacci(n) + 1 = A000045(n) + A001611(n). G.f.: (1+x-3x^2)/(1-2*x+x^3). (End) If n>=4, a(n) = floor(Phi*a(n-1)); Phi = (1 + sqrt(5))/2. - Philippe Deléham, Aug 08 2003 a(n) = F(n) + F(n+3) + 1, n >= -2 (where F(n) is the n-th Fibonacci number). - Zerinvary Lajos, Feb 01 2008 a(n) = 1 + (2/5)*((1/2) + (1/2)*sqrt(5))^n*sqrt(5) - (2/5)*sqrt(5)*((1/2) - (1/2)*sqrt(5))^n, with n >= 0. - Paolo P. Lava, Nov 21 2008 MAPLE A001588:=-(-1-z+3*z**2)/(z-1)/(z**2+z-1); # conjectured by Simon Plouffe in his 1992 dissertation with(combinat): seq(fibonacci(n)+fibonacci(n+3)+1, n=-2..35); # Zerinvary Lajos, Feb 01 2008 MATHEMATICA Fibonacci[Range[0, 100]]*2+1 (* Vladimir Joseph Stephan Orlovsky, Mar 19 2010 *) PROG (PARI) a(n)=2*fibonacci(n)+1 \\ Charles R Greathouse IV, Apr 06 2016 CROSSREFS Sequence in context: A161834 A141867 A163646 * A107029 A240180 A169942 Adjacent sequences:  A001585 A001586 A001587 * A001589 A001590 A001591 KEYWORD nonn,easy AUTHOR STATUS approved

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Last modified December 18 18:43 EST 2018. Contains 318243 sequences. (Running on oeis4.)