Köchel catalogue 225: The New Complete Edition" contains premiere performances of previously lost compositions and never recorded fragments, as well as key works in alternative versions and recordings of legendary historic performances. Köchel catalogue The Köchel catalogue () is a chronological catalogue of compositions by Wolfgang Amadeus Mozart, originally created by Ludwig von Köchel, in which the entries are abbreviated "K." and "KV". The numbers of the Köchel catalogue reflect the continuing establishment of a complete chronology of Mozart's works, and provide a shorthand reference to the compositions. According to Köchel's counting, "Requiem in D minor" is the 626th piece Mozart composed,
Stirling numbers of the first kind Stirling numbers of the first kind In mathematics, especially in combinatorics, Stirling numbers of the first kind arise in the study of permutations. In particular, the Stirling numbers of the first kind count permutations according to their number of cycles (counting fixed points as cycles of length one). The original definition of Stirling numbers of the first kind was algebraic. These numbers, usually written "s"("n", "k"), are signed integers whose sign, positive or negative, depends on the parity of "n" − "k". Afterwards, the absolute values of these numbers, |"s"("n", "k")|, which are known as unsigned Stirling numbers of the