OFFSET
1,1
COMMENTS
Relative density in the primes is 0, see Jones theorem 5.5.
LINKS
Charles R Greathouse IV, Table of n, a(n) for n = 1..500
Rafe Jones, The density of prime divisors in the arithmetic dynamics of quadratic polynomials, J. Lond. Math. Soc. (2) 78 (2) (2008), pp. 523-544.
FORMULA
a(n) << exp(k^n) for some constant k > 0, see Jones theorem 6.1. In particular this sequence is infinite. - Charles R Greathouse IV, Sep 28 2014
EXAMPLE
MATHEMATICA
Select[Table[d=0; t=0; Do[t=Mod[t^2+1, Prime[j]]; If[t==0, d=1], {k, 1, Prime[j]}]; If[d==1, Prime[j], 0], {j, 1, 1000}], #!=0&] (* Vaclav Kotesovec, Oct 04 2014 *)
PROG
(PARI) is(p)=my(v=List([1]), t=1); while(t, t=(t^2+1)%p; for(i=1, #v, if(v[i]==t, return(0))); listput(v, t)); isprime(p)
CROSSREFS
KEYWORD
nonn
AUTHOR
Charles R Greathouse IV, Sep 28 2014
STATUS
approved