[seqfan] Re: [math-fun] count of terms in cyclotomic polynomial

[wouter meeussen]

if seq_z(n)  equals   mu(n) Sum(d|n,  phi(d) mu(d) )
then, for all sqarefree n, with prime decomposition p*q*r*..*z
seq_z[n] = (p-2)*(q-2)*(r-2)*...*(z-2)

still boring?

W.