// output of ./demo/gf2n/lfsr-trace0-generators-demo.cc:
// Description:
//% Count primitive elements with trace==0 in GF(2**n)
//% (cf. OEIS sequences A192211 and A152049).
//% Fast method using class mersenne_coprime.

arg 1: 8 == n  [Bits in word (n>=2)]  default=8
  ct =72