%N Prime numbers p for which there is exactly one root x of x^3 - x - 1 in F_p and x is a primitive root mod p.
%C Gil, Weiner, & Zara prove that there is a unique complete Padovan sequence in F_p for each prime p in this sequence, which is generated by x. - _Charles R Greathouse IV_, Nov 26 2014
%H Juan B. Gil, Michael D. Weiner and Catalin Zara, <a href="http://www.fq.math.ca/Papers1/45-1/quartgil01_2007.pdf">Complete Padovan sequences in finite fields</a>, The Fibonacci Quarterly, Volume 45 Number 1, Feb 2007, pp. 64-75, see p. 71.
%o (PARI) is(n)=if(!isprime(n), return(0)); my(f=factormod('x^3-'x-1,n)[,1]); f=select(t->poldegree(t)==1, f); #f==1 && znorder(-polcoeff(f, 0))==n-1 \\ _Charles R Greathouse IV_, Nov 26 2014
%Y Cf. A134573, A134574.
%A _Gary W. Adamson_, Nov 01 2007
%E Corrected and extended by _Charles R Greathouse IV_, Nov 26 2014
%E New name from _Charles R Greathouse IV_, Nov 26 2014