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 A247981 Primes dividing nonzero terms in A003095: the iterates of x^2 + 1 starting at 0. 12
 2, 5, 13, 41, 137, 149, 229, 293, 397, 509, 661, 677, 709, 761, 809, 877, 881, 1217, 1249, 1277, 1601, 2053, 2633, 3637, 3701, 4481, 4729, 5101, 5449, 5749, 5861, 7121, 7237, 7517, 8009, 8089, 8117, 8377, 9661, 14869, 14897, 18229, 19609, 20369, 20441, 21493, 22349, 23917, 24781, 24977, 25717 (list; graph; refs; listen; history; text; internal format)
 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 2 and 13 are in the sequence since A003095(4) = 26. 3 is not in the sequence since it does not divide any member of A003095. 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(), 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 Cf. A003095, A248218, A248219. Sequence in context: A274909 A263308 A288388 * A149868 A007269 A179264 Adjacent sequences:  A247978 A247979 A247980 * A247982 A247983 A247984 KEYWORD nonn AUTHOR Charles R Greathouse IV, Sep 28 2014 STATUS approved

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Last modified October 23 12:54 EDT 2019. Contains 328345 sequences. (Running on oeis4.)