A138919 - OEIS

%I #19 Nov 11 2019 10:25:03

%S 5,7,18,20,21,30,34,36,38,52,54,60,90,104,117,123,146,159,179,182,229,

%T 278,388,405,410,439,552,557,735,806,807,1220,1272,1568,1688,1696,

%U 1710,1814,2136,2262,2288,2862,3679,3814,4058,4304,4480,5070,5136,5154

%N Indices k such that A020510(k)=Phi[k](-11) is prime, where Phi is a cyclotomic polynomial.

%C Larger values are probable primes.

%H Robert Price, <a href="/A138919/b138919.txt">Table of n, a(n) for n = 1..91</a>

%H Yves Gallot, <a href="http://yves.gallot.pagesperso-orange.fr/papers/cyclotomic.html">Cyclotomic polynomials and prime numbers</a>

%H <a href="/index/Cy#CyclotomicPolynomialsValuesAtX">Index entries for cyclotomic polynomials, values at X</a>

%t Select[Range[1000], PrimeQ[Cyclotomic[#, -11]] &]

%o (PARI) for( i=1,999, ispseudoprime( polcyclo(i,-11)) & print1(",",i)) /* use ...subst(polcyclo(i),x,-11)... in PARI < 2.4.2 */

%Y Cf. A020510, A138920-A138940, A070518-A070527.

%K nonn

%O 1,1

%A _M. F. Hasler_, Apr 04 2008

%E Edited by _T. D. Noe_, Oct 30 2008

%E a(32)-a(44) from _Robert Price_, Mar 16 2012

%E a(45)-a(50) from _Robert Price_, Apr 14 2012