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%I #15 Mar 13 2015 23:50:30
%S 2,1,1,2,1,2,1,2,2,2,1,3,1,2,3,2,1,3,1,3,3,2,1,3,2,2,2,3,1,3,1,2,3,2,
%T 3,3,1,2,3,3,1,3,1,3,3,2,1,3,2,3,3,3,1,3,3,3,3,2,1,3,1,2,3,2,3,3,1,3,
%U 3,3,1,3,1,2,3,3,3,3,1,3,2,2,1,3,3,2
%N The number of distinct coefficients in the n-th cyclotomic polynomial.
%C a(n) = 1 if n is a prime.
%C The sum of the coefficients in the n-th cyclotomic polynomial is given by A020500.
%C The first occurrence of 4 in this sequence is a(105).
%H T. D. Noe, <a href="/A230798/b230798.txt">Table of n, a(n) for n = 1..10000</a>
%e a(12)=3 because the distinct coefficients of the 12th cyclotomic polynomial, x^4-x^2+1, are 0, 1 and -1.
%t Table[Length[Union[CoefficientList[Cyclotomic[n, x], x]]], {n, 100}] (* _T. D. Noe_, Dec 09 2013 *)
%o (PARI) a(n) = #vecsort(Vec(polcyclo(n)),,8)
%Y Cf. A020500, A230799.
%Y Cf. A231611 (least k for which cyclotomic(k) has n distinct terms).
%K nonn
%O 1,1
%A _Colin Barker_, Oct 30 2013
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