#* http://rosettacode.org/wiki/Catalan_numbers
  Generate the first 15 Catalan numbers
*#

catalan = { n |
  true? n == 0
    { 1 }
    { (2 * ( 2 * n - 1) / ( n + 1 )) * catalan(n - 1) }
}

0.to 15 { n |
  p "#{n} - #{catalan n}"
}