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%I #8 Feb 23 2014 02:12:10
%S 1,2,3,4,5,6,7,10,16,17,26,32,104,109,120,133,312,546,608,2274,2527,
%T 2932,4462,4680,6001,7103,17402,17874,20664,26341,27954,32869,36204,
%U 41521,49065,64172,66318,196078
%N Indices of primes in the tribonacci-like sequence, A214825.
%C a(39) > 2*10^5.
%H Tony D. Noe and Jonathan Vos Post, <a href="http://www.cs.uwaterloo.ca/journals/JIS/VOL8/Noe/noe5.html">Primes in Fibonacci n-step and Lucas n-step Sequences</a>, J. of Integer Sequences, Vol. 8 (2005), Article 05.4.4
%t a={1,3,3}; Print[1];Print[2]; For[n=3, n<=1000, n++, sum=Plus@@a; If[PrimeQ[sum], Print[n]]; a=RotateLeft[a]; a[[3]]=sum]
%Y Cf. A001590, A100683, A231574, A231575, A232542, A214899, A230607, A020992, A232498, A214727, A081172, A214752, A141523,A214825, A235862.
%K nonn
%O 1,2
%A _Robert Price_, Feb 22 2014