%I A072226
%S A072226 2,3,4,5,6,7,8,9,10,12,13,14,15,16,17,19,22,24,26,27,30,31,32,33,34,38,
%T A072226 40,42,46,49,56,61,62,65,69,77,78,80,85,86,89,90,93,98,107,120,122,126,
%U A072226 127,129,133,145,150,158,165,170,174,184,192,195,202,208,234,254,261
%N A072226 Values of n for which Phi_n(2) is prime, where Phi_n is the n-th cyclotomic 
               polynomial.
%C A072226 Numbers n for which A019320(n) is prime. The prime n in this sequence 
               are in A000043, which produce the Mersenne primes. If 2p is in this 
               sequence, with p prime, then p is a Wagstaff number, A000978. - T. 
               D. Noe, Apr 02 2008
%C A072226 While the sequence looks quite dense for small values, note that there 
               are only 10 values in the interval [700,1200]. - M. F. Hasler (www.univ-ag.fr/
               ~mhasler), Apr 03 2008
%D A072226 Yves Gallot, Cyclotomic polynomials and prime numbers (November 12, 2000; 
               revised January 5, 2001)
%H A072226 T. D. Noe, <a href="b072226.txt">Table of n, a(n) for n=1..277</a> (initial 
               234 terms from Yves Gallot)
%H A072226 Joerg Arndt, <a href="http://www.jjj.de/fxt/#fxtbook">Fxtbook</a>
%H A072226 Yves Gallot, <a href="http://perso.wanadoo.fr/yves.gallot/papers/cyclotomic.html">
               Cyclotomic polynomials and prime numbers</a>
%H A072226 <a href="Sindx_Cy.html#CyclotomicPolynomialsValuesAtX">Index entries 
               for cyclotomic polynomials, values at X</a>
%t A072226 Select[Range[600], PrimeQ[Cyclotomic[ #, 2]]&]
%o A072226 (PARI) for( i=1,999, ispseudoprime( polcyclo(i,2)) && print1( i",")) 
               /* for PARI < 2.4.2 use ...subst(polcyclo(i),x,2)... */ - M. F. Hasler 
               (www.univ-ag.fr/~mhasler), Apr 03 2008
%Y A072226 Cf. A138920-A138940.
%Y A072226 Sequence in context: A102823 A004775 A004744 this_sequence A074402 A094270 
               A125705
%Y A072226 Adjacent sequences: A072223 A072224 A072225 this_sequence A072227 A072228 
               A072229
%K A072226 nonn
%O A072226 1,1
%A A072226 Reiner Martin (reinermartin(AT)hotmail.com), Jul 04 2002