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 A123108 a(0)=1, a(1)=0, a(2)=1, a(3)=1, a(n)=a(n-1)+a(n-2)-a(n-3) for n>3. 3

%I

%S 1,0,1,1,2,2,3,3,4,4,5,5,6,6,7,7,8,8,9,9,10,10,11,11,12,12,13,13,14,

%T 14,15,15,16,16,17,17,18,18,19,19,20,20,21,21,22,22,23,23,24,24,25,25,

%U 26,26,27,27,28,28,29,29,30,30,31,31,32,32,33,33,34,34,35,35,36,36,37,37

%N a(0)=1, a(1)=0, a(2)=1, a(3)=1, a(n)=a(n-1)+a(n-2)-a(n-3) for n>3.

%C Diagonal sums of triangle A123110. [From _Philippe Deléham_, Oct 08 2009]

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

%F G.f.: (1-x+x^3)/(1-x-x^2+x^3)

%F a(n)=A110654(n-1). - _R. J. Mathar_, Jun 18 2008

%F a(n)=1/4[1-(-1)^(n-1)]+1/2*(n-1)+[C(2*n,n) mod 2] [From _Paolo P. Lava_, Nov 19 2008]

%Y Cf. A065033.

%K nonn,easy

%O 0,5

%A _Philippe Deléham_, Sep 28 2006

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Last modified June 16 06:46 EDT 2019. Contains 324145 sequences. (Running on oeis4.)