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%I #14 Nov 11 2019 10:26:24
%S 3,7,10,11,12,13,24,28,47,48,49,56,57,88,90,92,108,110,116,120,127,
%T 134,141,149,161,181,198,202,206,236,248,288,357,384,420,458,500,530,
%U 536,619,620,694,798,897,929,981,992,1064,1134,1230,1670,1807,2094,2369
%N Indices k such that A019323(k)=Phi[k](5) is prime, where Phi is a cyclotomic polynomial.
%C Can there be an odd multiple of 5 in this sequence?
%H Robert Price, <a href="/A138935/b138935.txt">Table of n, a(n) for n = 1..110</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[#, 5]] &]
%o (PARI) for( i=1,999, ispseudoprime( polcyclo(i,5)) &&& print1( i",")) /* use ...subst(polcyclo(i),x,5)... in PARI < 2.4.2 */
%Y Cf. A019323, A138920-A138940.
%K nonn
%O 1,1
%A _M. F. Hasler_, Apr 03 2008
%E a(48)-a(54) from _Robert Price_, Apr 14 2012
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