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 A180672 a(n) = Fibonacci(n+7) - Fibonacci(7). 5

%I

%S 0,8,21,42,76,131,220,364,597,974,1584,2571,4168,6752,10933,17698,

%T 28644,46355,75012,121380,196405,317798,514216,832027,1346256,2178296,

%U 3524565,5702874,9227452,14930339,24157804,39088156,63245973

%N a(n) = Fibonacci(n+7) - Fibonacci(7).

%C The a(n+1) (terms doubled) are the Kn16 sums of the Fibonacci(n) triangle A104763. See A180662 for information about these knight and other chess sums.

%H Vincenzo Librandi, <a href="/A180672/b180672.txt">Table of n, a(n) for n = 0..280</a>

%H <a href="/index/Rec#order_03">Index entries for linear recurrences with constant coefficients</a>, signature (2,0,-1).

%F a(n) = F(n+7) - F(7) with F = A000045.

%F a(n) = a(n-1) + a(n-2) + 13 for n>1, a(0)=0, a(1)=8, and where 13 = F(7).

%F G.f.: x*(8 + 5*x)/((1 - x)*(1 - x - x^2)). - _Ilya Gutkovskiy_, Feb 24 2017

%F From _Colin Barker_, Feb 24 2017: (Start)

%F a(n) = (-13 + (2^(-1-n)*((1-sqrt(5))^n*(-29+13*sqrt(5)) + (1+sqrt(5))^n*(29+13*sqrt(5)))) / sqrt(5)).

%F a(n) = 2*a(n-1) - a(n-3) for n>2. (End)

%F a(n) = 8*A000071(n+2) + 5*A000071(n+1). - _Bruno Berselli_, Feb 24 2017

%p nmax:=40: with(combinat): for n from 0 to nmax do a(n):=fibonacci(n+7)-fibonacci(7) od: seq(a(n),n=0..nmax);

%t Fibonacci[7 +Range[0, 40]] -13 (* _G. C. Greubel_, Jul 13 2019 *)

%o (MAGMA) [Fibonacci(n+7) - Fibonacci(7): n in [0..40]]; // _Vincenzo Librandi_, Apr 24 2011

%o (PARI) concat(0, Vec(x*(8+5*x)/((1-x)*(1-x-x^2)) + O(x^40))) \\ _Colin Barker_, Feb 24 2017

%o (PARI) a(n)=fibonacci(n+7)-fibonacci(7) \\ _Charles R Greathouse IV_, Feb 24 2017

%o (Sage) [fibonacci(n+7)-13 for n in (0..40)] # _G. C. Greubel_, Jul 13 2019

%o (GAP) List([0..40], n-> Fibonacci(n+7)-13 ); # _G. C. Greubel_, Jul 13 2019

%Y Cf. A000045, A000071.

%Y Cf. A131524 (Kn11), A001911 (Kn12), A006327 (Kn13), A167616 (Kn14), A180671 (Kn15), A180672 (Kn16), A180673 (Kn17), A180674 (Kn18).

%K nonn,easy

%O 0,2

%A _Johannes W. Meijer_, Sep 21 2010

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Last modified April 10 02:39 EDT 2020. Contains 333392 sequences. (Running on oeis4.)