Commensurability and arithmetic equivalence for orthogonal   hypergeometric monodromy groups
  We compute invariants of quadratic forms associated to orthogonal hypergeometric groups of degree five. This allows us to determine some commensurabilities between these groups, as well as to say when some thin groups cannot be conjugate to each other. 
Jitendra Bajpai, Sandip Singh, Scott Thomson
math.GR math.NT