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Let Cn(x) be the n-th cyclotomic polynomial; a(n) is the first prime Cn(x) after Cn(1).
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%I #8 Sep 04 2022 23:03:33

%S 2,3,7,5,31,3,127,17,73,11,12207031,13,8191,43,151,257,131071,46441,

%T 524287,61681,368089,683,11111111111111111111111,241,

%U 705429635566498619547944801,2731,262657,15790321,7369130657357778596659,331,2147483647,65537,599479,43691

%N Let Cn(x) be the n-th cyclotomic polynomial; a(n) is the first prime Cn(x) after Cn(1).

%H Jinyuan Wang, <a href="/A085399/b085399.txt">Table of n, a(n) for n = 1..396</a>

%F a(n) = Phi(n,A085398(n)) where Phi(n,k) is the n-th cyclotomic polynomial evaluated at k. - _Jinyuan Wang_, Sep 04 2022

%e a(11)=12207031 because C11(x) is composite for x=2,3,4 and C11(5)=12207031 is prime.

%Y Cf. A084732, A085398, A307687.

%K nonn

%O 1,1

%A _Don Reble_, Jun 28 2003

%E More terms from _Jinyuan Wang_, Sep 04 2022