Founder Equivalents:
    
    Founder equivalents estimates the expected number
  of equally contributing founders that would be
  required to produce the observed genetic diversity
  in the current population.
  
fe = 1 / Σ(pi2)
Where pi is the proportion of the genes of the living, descendant population contributed by founder i.
    Founder Genome Equivalents:
    
    Founder genome equivalents estimates the expected number of
  equally contributing founders that would be required to
  produce the observed genetic diversity in the current
  population if no alleles had been lost to drift.
  
fg = 1 / Σ(pi2/ri)
Where pi is the proportion of the genes of the living, descendant population contributed by founder i, and ri is the allelic retention for founder i (estimated by gene drop).
Lacy RC. 1989. Analysis of founder representation in pedigrees: founder equivalents and founder genome equivalents. Zoo Biol 8:111-123.