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%I #18 Mar 15 2023 11:12:51
%S 1,7,13,14,24,91,48,28,39,168,120,182,183,336,312,56,288,273,180,168,
%T 624,840,22,364,120,1281,117,336,871,2184,993,112,1560,2016,48,546,
%U 1368,1260,2379,168,1723,4368,231,840,312,154,2257,728,336,840,3744,2562
%N Period of Perrin (0,2,3,2,5,5,..., A001608) sequence mod n.
%C Analogy to A001175, Pisano periods (or Pisano numbers): period of Fibonacci numbers mod n AND to A046738 for Perrin sequence, where a(n)=a(n-2)+a(n-3)
%C It appears that the n such that n-1 divides a(n) is the set of primes of the form x^2+23*y^2 (A033217). The discriminant of the characteristic polynomial of the Perrin sequence is -23. - _T. D. Noe_, Feb 23 2007
%H T. D. Noe, <a href="/A104217/b104217.txt">Table of n, a(n) for n=1..1000</a>
%t Table[a={0,2,3}; a=a0=Mod[a, n]; k=0; While[k++; s=a[[2]]+a[[1]]; a=RotateLeft[a]; a[[ -1]]=Mod[s,n]; a!=a0]; k, {n,100}] (* _T. D. Noe_, Oct 10 2006 *)
%Y Cf. A001175, A046738 and Perrin sequence A001608.
%K nonn
%O 1,2
%A _Anthony C Robin_, Mar 14 2005
%E More terms from _T. D. Noe_, Oct 10 2006
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