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%I #7 Jun 20 2015 14:43:23
%S 0,1,2,3,13,470,2957
%N Numbers n such that cyclotomic polynomial value Phi(7,n!) is prime.
%C Except for the values 0,1,2 and 3, terms correspond to probable primes.
%C a(8) > 6502.
%C Also, numbers n such that n! belongs to A100330. - _Michel Marcus_, May 30 2015
%e 3 is in the sequence because Phi(7,3!) = 1 + 6 + 6^2 + 6^3 + 6^4 + 6^5 + 6^6 = 55987 is prime.
%t Select[Range[0, 6502], PrimeQ[Cyclotomic[7, #!]] &]
%Y Cf. A002981, A002982, A046029, A200906.
%K nonn,more
%O 1,3
%A _Robert Price_, May 27 2015