login
A247561
Indices of primes in the tetranacci sequence A000288.
6
5, 6, 10, 11, 12, 13, 18, 30, 31, 36, 38, 97, 108, 150, 196, 221, 277, 532, 596, 2468, 2691, 3773, 4303, 5755, 8925, 10083, 11708, 14080, 19990, 24102, 34767, 35973, 39238, 49760, 97706
OFFSET
1,1
COMMENTS
a(36) > 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
MATHEMATICA
a={1, 1, 1, 1}; For[n=4, n<=1000, n++, sum=Plus@@a; If[PrimeQ[sum], Print[n]]; a=RotateLeft[a]; a[[4]]=sum]
Flatten[Position[LinearRecurrence[{1, 1, 1, 1}, {1, 1, 1, 1}, 10^5], _?PrimeQ]]- 1 (* Harvey P. Dale, Dec 20 2016 *)
KEYWORD
nonn,more
AUTHOR
Robert Price, Sep 27 2014
STATUS
approved