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%I #4 Oct 19 2017 03:14:05
%S 2,3,16,7,2205,17,174037,1600,45796,984
%N a(n) = the least positive number X such that Cn(X) is X-smooth, where Cn is the n-th cyclotomic polynomial and "X-smooth" means "has no prime factor greater than X".
%C Inspired by a conjecture of David W. Wilson: for each nonzero polynomial P with integer coefficients, there is an integer X such that P(X) is X-smooth. Certain cyclotomic polynomials seem to stress the conjecture, but no refutation is yet known. If a(11) exists, it is greater than 1,060,000.
%e a(5)=2205 because C5(2205) = 23650012729981 = 11*11*31*61*101*691*1481; and no prime factor is greater than 2205.
%K nonn
%O 1,1
%A _Don Reble_, Sep 20 2002