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 A098600 a(n) = Fibonacci(n-1) + Fibonacci(n+1) - (-1)^n. 9
 1, 2, 2, 5, 6, 12, 17, 30, 46, 77, 122, 200, 321, 522, 842, 1365, 2206, 3572, 5777, 9350, 15126, 24477, 39602, 64080, 103681, 167762, 271442, 439205, 710646, 1149852, 1860497, 3010350, 4870846, 7881197, 12752042, 20633240, 33385281, 54018522 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,2 COMMENTS Row sums of A098599. LINKS Vincenzo Librandi, Table of n, a(n) for n = 0..1000 Index entries for linear recurrences with constant coefficients, signature (0,2,1). FORMULA G.f.: (1+2*x) / ((1+x)*(1-x-x^2)). a(n) = Sum_{k = 0..n} binomial(k, n-k) + binomial(k-1, n-k-1). a(n) = A020878(n) - 1 = A001350(n) + 1. a(n) = Lucas(n) - (-1)^n. - Paul Barry, Dec 01 2004 a(n) = A181716(n+1). - Richard R. Forberg, Aug 30 2014 a(n) = [x^n] ( (1 + x + sqrt(1 + 6*x + 5*x^2))/2 )^n. exp( Sum_{n >= 1} a(n)*x^n/n ) = Sum_{n >= 0} Fibonacci(n+2)*x^n. Cf. A182143. - Peter Bala, Jun 29 2015 From Colin Barker, Jun 03 2016: (Start) a(n) = (-(-1)^n + ((1/2)*(1-sqrt(5)))^n + ((1/2)*(1+sqrt(5)))^n). a(n) = 2*a(n-2) + a(n-3) for n > 2. (End) E.g.f.: (2*exp(3*x/2)*cosh(sqrt(5)*x/2) - 1)*exp(-x). - Ilya Gutkovskiy, Jun 03 2016 MAPLE with(combinat): P:=proc(n) fibonacci(n-1)+fibonacci(n+1)-(-1)^n; end: seq(P(i), i=0..40); # Paolo P. Lava, Mar 09 2018 MATHEMATICA Table[-(-1)^n + LucasL[n], {n, 0, 39}] (* Alonso del Arte, Aug 30 2014 *) Table[Fibonacci[n - 1] + Fibonacci[n + 1] - (-1)^n, {n, 0, 40}] (* Vincenzo Librandi, Aug 31 2014 *) CoefficientList[ Series[-(1 + 2x)/(-1 + 2x^2 + x^3), {x, 0, 40}], x] (* or *) LinearRecurrence[{0, 2, 1}, {1, 2, 2}, 40] (* Robert G. Wilson v, Mar 09 2018 *) PROG (MAGMA) [Fibonacci(n-1) + Fibonacci(n+1) - (-1)^n: n in [0..50]]: // Vincenzo Librandi, Aug 31 2014 (PARI) a(n)=fibonacci(n-1) + fibonacci(n+1) - (-1)^n; \\ Joerg Arndt, Oct 18 2014 (PARI) Vec((1+2*x)/((1+x)*(1-x-x^2)) + O(x^30)) \\ Colin Barker, Jun 03 2016 CROSSREFS Cf. A000045, A008346, A182143. First differences of A014217 and A062724. Cf. A000032, A099925, A181716. Sequence in context: A238517 A099926 A181716 * A261866 A147766 A034420 Adjacent sequences:  A098597 A098598 A098599 * A098601 A098602 A098603 KEYWORD easy,nonn,changed AUTHOR Paul Barry, Sep 17 2004 STATUS approved

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Last modified March 21 20:31 EDT 2018. Contains 301041 sequences. (Running on oeis4.)