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%I #9 Nov 11 2019 13:48:00
%S 73,530713,6481,47763361,42521761,150094634909578633,
%T 13490012358249728401,282429005041,
%U 19966781110160346782368664772328944885905284750420567849,1076050302914923449767311155851656076154481
%N Primes of the form Phi(k, -9), where Phi is the cyclotomic polynomial.
%H Robert Price, <a href="/A291991/b291991.txt">Table of n, a(n) for n = 1..13</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[Table[Cyclotomic[k,-9], {k, 0, 100}], PrimeQ[#] &]
%Y Cf. A138921.
%K nonn
%O 1,1
%A _Robert Price_, Sep 07 2017