A partition in which no part occurs more than oneonce is called ''strict'', or is said to be a partition ''into distinct parts''. The function ''q''(''n'') gives the number of these strict partitions of the given sum ''n''. For example, ''q''(3) = 2 because the partitions 3 and 1 + 2 are strict, while the third partition 1 + 1 + 1 of 3 has repeated parts. The number ''q''(''n'') is also equal to the number of partitions of ''n'' in which only odd summands are permitted.<ref>{{cite book|first=Richard P.|last=Stanley|author-link=Richard P. Stanley|title=Enumerative Combinatorics 1 |series=Cambridge Studies in Advanced Mathematics|volume=49|publisher=Cambridge University Press|isbn=0-521-66351-2 |year=1997|at=Proposition 1.8.5}}</ref>
