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%I #21 Jun 20 2015 14:42:37
%S 0,1,2,4,5,21,44,64,244,268,2415
%N Numbers n such that cyclotomic polynomial value Phi(5,n!) is prime.
%C 2415 corresponds to a probable prime. - _Serge Batalov_, Nov 24 2011
%C a(12) > 15000. - _Robert Price_, Jun 20 2015
%e 5 is in the sequence because Phi(5,5!) = ((5!)^5-1)/(5!-1)= 209102521 is prime.
%t Do[If[PrimeQ[Cyclotomic[5, n!]], Print[n]], {n, 0, 600}]
%o (PARI) for(n=0,600,x=n!;if(isprime(eval(polcyclo(5))),print(n)))
%Y Cf. A002981, A002982, A046029, A046029.
%K nonn
%O 1,3
%A _Serge Batalov_, Nov 23 2011
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