PRIME SMARANDACHE EXPRESSION



Definition:
            x2      x3           x1
   E(n) = x1   +  x2   + ... + xn   , where n >= 2, with x1, x2, ..., xn > 1
   and have the greatest common divisor 1.

   There are infinitely many composite numbers of this form.
   
   Unsolved Problem:  Are there finitely or infinitely many primes of 
   this form?


References:                              y     x
  [1] Castillo, J., "Primes of the form x  +  y  ", <Mathematical Spectrum>,
      Vol. 29, No. 1, 1996/7, p. 21.
  [2] Castini, Peter, Letter to the Editor, <Mathematical Spectrum>, Vol. 28, 
      No. 3, 1995/6, p. 68.
  [3] Luca, Florian, "Products of Factorials in Smarandache Type Expressions",
      <Smarandache Notions Journal>, Vol. 8, No. 1-2-3, 1997, pp. 29-41.
  [4] Luca, Florian, "Perfect Powers in Smarandache Type Expressions",
      <Smarandache Notions Journal>, Vol. 8, No. 1-2-3, 1997, pp. 72-89.