A234696 Indices of primes in the tribonacci-like sequence, A214727.

1, 2, 3, 8, 16, 20, 64, 208, 364, 2652, 7763, 17280, 24104, 31823, 70864, 74008

Offset: 1

Author

Robert Price, Dec 29 2013

Keywords

• nonn

Comments

a(17) > 2*10^5.

Links

• Tony D. Noe and Jonathan Vos Post, Primes in Fibonacci n-step and Lucas n-step Sequences, J. of Integer Sequences, Vol. 8 (2005), Article 05.4.4

Crossrefs

Cf. A001590, A100683, A231574, A231575, A232542, A214899, A230607, A020992, A232498, A214727.

Programs

Mathematica

a={1, 2, 2}; Print[2]; Print[2]; For[n=3, n<=1000, n++, sum=Plus@@a; If[PrimeQ[sum], Print[n]]; a=RotateLeft[a]; a[[3]]=sum]
Position[LinearRecurrence[{1,1,1},{1,2,2},75000],?PrimeQ]-1//Flatten (* _Harvey P. Dale, Sep 02 2016 *)