Path: utzoo!attcan!uunet!ogicse!ucsd!ucbvax!ucbarpa.Berkeley.EDU!pathria From: pathria@ucbarpa.Berkeley.EDU (Anu Pathria) Newsgroups: comp.theory Subject: Re: partitioning problem Message-ID: <39840@ucbvax.BERKELEY.EDU> Date: 1 Dec 90 21:39:25 GMT References: <9011301618.AA00954@irt.watson.ibm.com> Sender: usenet@ucbvax.BERKELEY.EDU Reply-To: pathria@ucbarpa.Berkeley.EDU.UUCP (Anu Pathria) Organization: University of California, Berkeley Lines: 10 >The number of ways of partitioning n objects into k groups such >that * no group is empty * is given by the Stirling's number of the >second type i.e. > >S(n,k) = S(n-1,k-1) + k*S(n-1,k) > >Is there any formula for calculating the number of possible partitions >if * one or more groups may be empty * ? I must be missing something but shouldn't it be k^n-S(n,k) ? Brought to you by Super Global Mega Corp .com