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 A002571 From a definite integral. (Formerly M3802 N1553) 11
 1, 5, 10, 30, 74, 199, 515, 1355, 3540, 9276, 24276, 63565, 166405, 435665, 1140574, 2986074, 7817630, 20466835, 53582855, 140281751, 367262376, 961505400, 2517253800, 6590256025, 17253514249, 45170286749, 118257345970 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 COMMENTS a(n) are the row sums of the elements of the Golden Triangle (A180662) with alternating signs. [Alexander Adamchuk, Oct 18 2010] A002570(n)/A002571(n) approaches 1/sqrt(5) as n->infinity. - Sean A. Irvine, Apr 09 2014 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 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. L. R. Shenton, A determinantal expansion for a class of definite integral. Part 5. Recurrence relations, Proc. Edinburgh Math. Soc. (2) 10 (1957), 167-188. L. R. Shenton and K. O. Bowman, K.O., Second order continued fractions and Fibonacci numbers, Far East Journal of Applied Mathematics, 20(1), 17-31, 2005. FORMULA Appears to have g.f. x/[(1-3x+x^2)(1+x)^2]. - Ralf Stephan, Apr 14 2004 a(n) = (-1)^n*Sum[(-1)^(i+1)*(Fibonacci[i]*Fibonacci[i+1]),{i,1,n+1}] - Alexander Adamchuk, Jun 16 2006 From Paul D. Hanna, Feb 20 2009: (Start) Given g.f. A(x), then log(1+A(x)) = Sum_{n>=1} A000204(n)^2 * x^n/n where A000204 is the Lucas numbers. a(n) = (1/n)*[A000204(n)^2 + Sum_{k=1..n-1} A000204(k)^2*a(n-k)] for n>1, with a(1) = 1. (End) G.f.: -1 + 1/Product_{n>=1} (1 - Lucas(n)*x^n + (-1)^n*x^(2*n))^A006206(n), where A006206(n) is the number of aperiodic binary necklaces of length n with no subsequence 00. [Paul D. Hanna, Jan 07 2012] a(n) = 8*a(n-2) - 8*a(n-4) + a(n-6) + 2(-1)^n, n>6. - Sean A. Irvine, Apr 09 2014 a(n) - a(n-2) = Fibonacci(n+1)^2. - Peter Bala, Aug 30 2015 EXAMPLE From Paul D. Hanna, Feb 20 2009: (Start) G.f.: A(x) = x + 5*x^2 + 10*x^3 + 30*x^4 + 74*x^5 + 199*x^6 +... log(1+A(x)) = x + 3^2*x^2/2 + 4^2*x^3/3 + 7^2*x^4/4 + 11^2*x^5/5 +... (End) G.f.: A(x) = -1 + 1/((1-x-x^2) * (1-3*x^2+x^4) * (1-4*x^3-x^6) * (1-7*x^4+x^8) * (1-11*x^5-x^10)^2 * (1-18*x^6+x^12)^2 * (1-29*x^7-x^14)^4 * (1-47*x^8+x^16)^5 * (1-76*x^9-x^18)^8 *...* (1 - Lucas(n)*x^n + (-1)^n*x^(2*n))^A006206(n) *...). [Paul D. Hanna, Jan 07 2012] MAPLE A002571:=-(-1-4*z-z**2+z**3)/(z**2-3*z+1)/(1+z)**2; # Conjectured (probably correctly) by Simon Plouffe in his 1992 dissertation. PROG (PARI) {a(n)=polcoeff(exp(sum(m=1, n, (fibonacci(m+1)+fibonacci(m-1))^2*x^m/m)+x*O(x^n)), n)} \\ Paul D. Hanna, Feb 20 2009 CROSSREFS Cf. A064831, A077916, A000045, A000204 (Lucas), A006206. Cf. A001654, A180662 - The Golden Triangle. [Alexander Adamchuk, Oct 18 2010] Sequence in context: A156302 A156234 A048010 * A077916 A189315 A056422 Adjacent sequences:  A002568 A002569 A002570 * A002572 A002573 A002574 KEYWORD nonn AUTHOR EXTENSIONS More terms from Max Alekseyev and Alexander Adamchuk, Oct 18 2010 STATUS approved

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Last modified October 14 05:08 EDT 2019. Contains 327995 sequences. (Running on oeis4.)