%I A138940
%S A138940 2,4,10,12,14,19,23,24,36,38,39,48,62,93,106,120,134,150,196,317,320,
%T A138940 385,586,597,654,738,945
%N A138940 Indices n such that A019328(n)=Phi[n](10) is prime, where Phi is a cyclotomic 
               polynomial.
%C A138940 "Unique [period] primes" (A040017) are often of the form Phi[k](10) or 
               Phi[k](-10).
%H A138940 C. Caldwell, <a href="http://primes.utm.edu/glossary/page.php?sort=UniquePrime">
               Unique Primes</a>.
%H A138940 <a href="Sindx_Cy.html#CyclotomicPolynomialsValuesAtX">Index entries 
               for cyclotomic polynomials, values at X</a>
%o A138940 (PARI) for( i=1,999, isprime( polcyclo(i,10)) && print1( i",")) /* for 
               PARI < 2.4.2 use ...subst(polcyclo(i,x),x,10)... */
%Y A138940 Cf. A019328, A040017.
%Y A138940 Sequence in context: A136818 A029984 A101519 this_sequence A129412 A113536 
               A081887
%Y A138940 Adjacent sequences: A138937 A138938 A138939 this_sequence A138941 A138942 
               A138943
%K A138940 nonn,more
%O A138940 1,1
%A A138940 M. F. Hasler (www.univ-ag.fr/~mhasler), Apr 03 2008