PRIME DENSITIES FOR SECOND ORDER TORSION SEQUENCES
Peter Stevenhagen · 2007
The set of primes X dividing the terms of a second order linear recurrent integer sequence X has a natural description in terms of the initial quotient q of X and the root quotient r of the underlying recurrence. We call X torsion if the residue class of q in the group associated to r is torsion. We prove that for such X, the set X has positive rational density in the set of all primes. We compute the density explicitly for a 'generic' class of examples.