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A137357 a(n) = Sum_{k <= n/2 } binomial(n-2k, 3k+1). 3

%I

%S 0,1,2,3,4,5,7,12,23,44,80,138,230,379,629,1060,1810,3109,5336,9120,

%T 15521,26349,44713,75949,129177,219918,374521,637699,1085401,1846804,

%U 3141826,5344988,9093989,15474230,26332515,44810670,76253683,129755543,220790480

%N a(n) = Sum_{k <= n/2 } binomial(n-2k, 3k+1).

%D D. E. Knuth, The Art of Computer Programming, Vol. 4A, Section 7.1.4.

%H <a href="/index/Rec">Index entries for linear recurrences with constant coefficients</a>, signature (3,-3,1,0,1).

%F G.f.: x*(x-1) / (x^5+x^3-3*x^2+3*x-1). - _Colin Barker_, Jan 23 2013

%Y Cf. A137356-A137361, A136444.

%K nonn,easy

%O 0,3

%A _Don Knuth_, Apr 11 2008

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Last modified March 20 05:17 EDT 2019. Contains 321344 sequences. (Running on oeis4.)